Foam ionomer compositions and uses thereof

ABSTRACT

Components for articles of footwear and athletic equipment are provided including a foam. A variety of foams and foam components are provided. The articles include a composition having a foam structure, wherein the composition includes an ionomeric polymer and a plurality of cations, wherein the ionomeric copolymer is crosslinked by the cations. The crosslinks are ionic, so in some aspects the composition is free or essentially free of any covalent crosslinks between the ionomers. In particular, midsoles including the foams are provided for use in an article of footwear. Methods of making the compositions and foams are provided, as well as methods of making an article of footwear including one of the foam components. In some aspects, the foams and foam components can be made by injection molding or injection molding followed by compression molding.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 17/192,625, having the title “FOAM IONOMER COMPOSITIONS ANDUSES THEREOF,” filed Mar. 4, 2021, which is a continuation of U.S.Non-Provisional application Ser. No. 15/975,882, having the title “FOAMIONOMER COMPOSITIONS AND USES THEREOF,” filed May 10, 2018, now issuedas U.S. Pat. No. 10,982,067, which claims the benefit of and priority toU.S. Provisional Application Ser. No. 62/504,490 having the title “FOAMIONOMER COMPOSITIONS AND USES THEREOF,” filed May 10, 2017, the contentsof which are incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure generally relates to foams formed of ionomericpolymers, and in particular to foams formed of ionomeric polymers whichare suitable for the footwear and related industries and uses thereof.

BACKGROUND

The design of athletic equipment and apparel as well as footwearinvolves a variety of factors from the aesthetic aspects, to the comfortand feel, to the performance and durability. While design and fashionmay be rapidly changing, the demand for increasing performance in themarket is unchanging. To balance these demands, designers employ avariety of materials and designs for the various components that make upathletic equipment and apparel as well as footwear.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present disclosure will be readily appreciatedupon review of the detailed description, described below, when taken inconjunction with the accompanying drawings.

FIG. 1 is an elevation view of an article of footwear with a solecomponent according to an aspect of the invention.

FIG. 2 is an exploded view of the sole component of the article offootwear of FIG. 1 .

FIG. 3 is a plan view of the bottom of the sole component of the articleof footwear of FIG.

FIG. 4 is a bottom view of an insert for use in a sole component of anarticle of footwear.

FIG. 5 is a top view of the insert of FIG. 4 inserted in a first portionto form a sole component.

DETAILED DESCRIPTION

The present disclosure is directed to a foam formed of ionomericpolymers, i.e., ionomer foam. The ionomer foams are formed frompolymeric compositions comprising one or more ionomeric copolymer.Examples of ionomeric polymers include polymers which have one or morecarboxylic acid moiety present in the polymeric backbone, on one or moreside chains, or both in the polymeric backbone and on one or more sidechains. The one or more carboxylic acid moiety of the ionomericcopolymer can include a free carboxylic acid, a salt of a carboxylicacid, or an anhydride of a carboxylic acid. In particular examples, thecarboxylic acid moiety can be an acrylic acid moiety or a methacrylicacid moiety. The ionomer foam of the present disclosure is suitable foruse in a variety of articles including for athletic equipment andapparel, particularly footwear (e.g., athletic footwearmidsoles/outsoles). As discussed below, the ionomer foam exhibits aunique balance of properties such as high energy return, high splittear, low specific gravity, and low compression set. Furthermore, theionomer foam can also be reprocessed with minimal loss in physicalproperties (e.g., for recycling), providing a solution for materialssustainability.

It has been found that ionomeric polymers having particular ranges offlexural modulus (e.g., less than 100 Mega Pascals (MPa)), hardness(e.g., less than 45 MPa) can be used to produce ionomer foams suitablefor use as cushioning materials, such as for use in apparel, articles offootwear, and sports equipment. It has been found that these ionomericpolymers can be used to produce ionomer foams having unexpectedly highlevels of energy return and other properties making them useful ascushioning materials for use in articles of footwear, particularly whenthese ionomeric polymers are foamed by an injection molding processusing supercritical fluids as physical blowing agents. The use of fattyacid modified ionomeric polymers has also been found to produce ionomerfoams having unexpectedly high levels of energy return and otherproperties making them useful as cushioning materials for use inarticles of footwear. Additionally, the storage modulus (e.g., overtemperatures from −10 degrees Celsius to 40 degrees Celsius) and the tandelta (δ) of the ionomer polymers have been identified as beingpredictive of whether or not the ionomer polymers will be produce foamssuitable for use as cushioning materials.

In a first aspect, the present disclosure is directed to an articlecomprising a composition, wherein the composition comprises one or moreionomeric copolymers, wherein each of the one or more ionomericcopolymers includes chain units derived from one or more olefins andchain units derived from one or more ethylenically-unsaturated acidgroups; and a plurality of cations, wherein the cations ionicallycrosslink anionic groups from the acid groups in the ionomericcopolymers; wherein the composition has a foam structure having aspecific gravity of less than 0.7.

In a second aspect, the present disclosure is directed to an articlecomprising a composition, wherein the composition comprises a pluralityof ionomeric copolymers, wherein each of the ionomeric copolymerscomprises a plurality of a first repeat unit having a formula accordingto Formula I and a plurality of a second repeat unit having a formulaaccording to Formula II, and

a plurality of cations, wherein each of the cations is crosslinking twoor more of the second repeat units; wherein each occurrence of R¹ isindependently none, a substituted or unsubstituted C₁-C₈ alkyl, or asubstituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence ofR² is independently hydrogen, a halogen, a substituted or unsubstitutedC₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substitutedor unsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, asubstituted or unsubstituted C₁-C₈ alkoxy, or a substituted orunsubstituted C₃-C₁₂ alkyl ester; wherein each occurrence of R³ isindependently hydrogen, a substituted or unsubstituted C₁-C₈ alkyl, or asubstituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence ofR⁵ is independently a hydrogen, a halogen, a substituted orunsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl,a substituted or unsubstituted phenyl, a substituted or unsubstitutedalkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy, or asubstituted or unsubstituted C₃-C₁₂ alkyl ester; wherein each occurrenceof R⁶ is independently none, a substituted or unsubstituted C₁-C₈ alkyl,a substituted or unsubstituted C₂-C₈ alkenyl, a substituted orunsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, or asubstituted or unsubstituted C₁-C₈ alkoxy; wherein each occurrence of R⁷is independently a carboxylate, a sulfate, a sulfonate, a nitrate, aphosphate, a phosphonate, or another negatively charged functionalgroup; and wherein the composition is a foam having a specific gravityof less than 0.7.

In a third aspect, the present disclosure is directed to a method ofmaking an article, the method comprising: receiving a compositioncomprising one or more ionomeric copolymers, wherein each of the one ormore ionomeric copolymers includes chain units of one or more olefinsand one or more acid groups; and a plurality of cations, wherein thecations ionically crosslink anionic groups in the ionomeric copolymers;and physically foaming the composition, forming a foam having a specificgravity of less than 0.7.

In a fourth aspect, the present disclosure is directed to a method ofmaking an article, the method comprising receiving a compositioncomprising: a plurality of ionomeric copolymers, wherein each of theionomeric copolymers comprises a plurality of a first repeat unit havinga formula according to Formula I and a plurality of a second repeat unithaving a formula according to Formula II, and

a plurality of cations, wherein each of the cations is crosslinking twoor more of the second repeat units; wherein each occurrence of R¹ isindependently none, a substituted or unsubstituted C₁-C₈ alkyl, or asubstituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence ofR² is independently hydrogen, a halogen, a substituted or unsubstitutedC₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substitutedor unsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, asubstituted or unsubstituted C₁-C₈ alkoxy, or a substituted orunsubstituted C₃-C₁₂ alkyl ester; wherein each occurrence of R³ isindependently hydrogen, a substituted or unsubstituted C₁-C₈ alkyl, or asubstituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence ofR⁵ is independently a hydrogen, a halogen, a substituted orunsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl,a substituted or unsubstituted phenyl, a substituted or unsubstitutedalkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy, or asubstituted or unsubstituted C₃-C₁₂ alkyl ester; wherein each occurrenceof R⁶ is independently none, a substituted or unsubstituted C₁-C₈ alkyl,a substituted or unsubstituted C₂-C₈ alkenyl, a substituted orunsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, or asubstituted or unsubstituted C₁-C₈ alkoxy; and wherein each occurrenceof R⁷ is independently a carboxylate, a sulfate, a sulfonate, a nitrate,a phosphate, a phosphonate, or another negatively charged functionalgroup; and physically foaming the composition, forming a foam having aspecific gravity of less than 0.7.

In a fifth aspect, the present disclosure is directed to a method offorming a foam article, the method comprising: forming a melt of a firstcomposition at a first pressure, wherein the first composition comprisesone or more ionomeric copolymers, wherein each of the one or moreionomeric copolymers includes chain units of one or more olefins and oneor more ethylenically-unsaturated acid groups; a plurality of cations;and a fluid; introducing the melt to a second pressure less than thefirst pressure, causing a portion of the fluid to leave the melt andforming a foam structure in the melt; and simultaneously with theintroducing or sequentially following the introducing, cooling the meltto a temperature below a melting point of the first composition, causinga portion of the plurality of cations to ionically crosslink anionicgroups from the acid groups in the ionomeric copolymers, forming thefoamed article.

In a sixth aspect, the present disclosure is directed to a method offorming a foam article, the method comprising: forming a melt of a firstcomposition at a first pressure, wherein the first composition comprisesa plurality of ionomeric copolymers, wherein each of the ionomericcopolymers comprises a plurality of a first repeat unit having a formulaaccording to Formula I and a plurality of a second repeat unit having aformula according to Formula II, and

a plurality of cations, and a fluid; introducing the melt to a secondpressure less than the first pressure, causing a portion of the fluid toleave the melt and forming a foam structure in the melt; andsimultaneously with the introducing or sequentially following theintroducing, cooling the melt to a temperature below a melting point ofthe first composition, causing a portion of the plurality of cations toionically crosslink two or more of the second repeat units, forming thefoamed article.

In a seventh aspect, the present disclosure is directed to a foamarticle made by a process comprising: cutting or grinding a previouslymolded foam article to form particulates, wherein the recycled foamarticle is an article described herein; melting the particulates intopellets to form the recycled material; and forming a foam article via amethod according to a method described herein, wherein the recycledmaterial is used to form the melt of the first composition.

Footwear 10 is an exemplary article of athletic footwear that includesthe ionomer foam of the present disclosure. While illustrated as arunning shoe, footwear 10 may alternatively be configured for anysuitable athletic performance, such as baseball shoes, basketball shoes,soccer/global football shoes, American football shoes, running shoes,cross-trainer shoes, cheerleading shoes, golf shoes, and the like. Whilean athletic shoe is exemplified in FIG. 1 , it will be readilyunderstood that some of the terminology employed will also apply toother articles of footwear or to other styles of shoe. Footwear 10includes an upper 12 and a sole component 14 secured to upper 12. Solecomponent 14 can be secured to upper 12 by adhesive or any othersuitable means. As used herein, the sole component 14 can be amonolithic component formed entirely of the ionomer foam material asdescribed herein, or a multi-component assembly formed of a plurality ofmonolithic components, where at least one of the monolithic componentsis formed entirely of the ionomer foam material as described herein.

Footwear 10 has a medial, or inner, side 16 and a lateral, or outer,side 18. For ease of discussion, footwear 10 can be divided into threeportions: a forefoot portion 20, a midfoot portion 22, and a heelportion 24. Portions 20, 22, and 24 are not intended to demarcateprecise areas of footwear 10. Rather, portions 20, 22, and 24 areintended to represent respective areas of footwear 10 that provide aframe of reference during the following discussion. Unless indicatedotherwise, directional terms used herein, such as rearwardly, forwardly,top, bottom, inwardly, downwardly, upwardly, etc., refer to directionsrelative to footwear 10 itself. Footwear 10 is shown in FIG. 1 in asubstantially horizontal orientation, as it would be positioned on ahorizontal surface when worn by a wearer. However, it is to beappreciated that footwear 10 need not be limited to such an orientation.Thus, in FIG. 1 , rearwardly is toward heel portion 24 (to the right asseen in FIG. 1 ), forwardly is toward forefoot portion 20 (to the leftas seen in FIG. 1 ), and downwardly is toward the bottom of the page asseen in FIG. 1 . Top refers to elements toward the top of the view inFIG. 1 , while bottom refers to elements toward the bottom of the viewin FIG. 1 . Inwardly is toward the center of footwear 10, and outwardlyis toward the outer peripheral edge of footwear 10.

In some aspects, the component is a sole component, such as a solecomponent 14 depicted in FIGS. 1-5 , that includes an ionomer foamdescribed herein. In some aspects, the component is an insert such asinsert 36 or insert 60 depicted in FIGS. 4-5 that includes an ionomerfoam described herein. The sole components and inserts for solecomponents can be made partially or entirely of an ionomer foamdescribed herein. Any portion of a sole component or an insert for asole component can be made of an ionomer foam described herein. Forexample, first portion 26 of the sole component (optionally includingthe ground engaging lower surface 44, such as the plurality ofprojections 46 and/or the groove 48 surrounding the projections), theentire insert 36, portions 62 or 64 of insert 60, a separate outsolecomponent, or any combination thereof, can include an ionomer foam asdescribed herein. The sole components and inserts can be made by foamingionomeric polymers as described herein, for example by injection moldingor by injection molding followed by compression molding as describedherein. In some aspects, the ionomer foams can be formed by physicalfoaming of the compositions. The ionomer foams and components candemonstrate improved physical properties including one or more of anenhanced energy return, and enhanced split tear, a decreased specificgravity, or a combination thereof.

Sole component 14, which is generally disposed between the foot of thewearer and the ground, provides attenuation of ground reaction forces(i.e., imparting cushioning), traction, and may control foot motions,such as pronation. As with conventional articles of footwear, solecomponent 14 can include an insole (not shown) located within upper 12.In some aspects, the sole component is an insole or sockliner or is amulti-component assembly including an insole or sockliner, can furtherinclude an insole or sockliner located within the upper, where theinsole or sockliner is formed entirely or partially of an ionomer foamdescribed herein. Articles of footwear described herein can include aninsole or sockliner formed entirely or partially of an ionomer foamdescribed herein.

As can be seen in FIG. 2 , sole component 14 consists of a first portion26 having an upper surface 27 with a recess 28 formed therein. Uppersurface 27 is secured to upper 12 with adhesive or other suitablefastening means. A plurality of substantially horizontal ribs 30 isformed on the exterior of first portion 26. In certain aspects, ribs 30extend from a central portion of forefoot portion 20 on medial side 16rearwardly along first portion 26, around heel portion 24 and forwardlyon lateral side 18 of first portion 26 to a central portion of forefootportion 20.

First portion 26 provides the external traction surface of solecomponent 14. In certain aspects it is to be appreciated that a separateoutsole component could be secured to the lower surface of first portion26. When a separate outsole component is secured to the lower surface offirst portion 26, the first portion 26 is a midsole component. In someaspects, the article is a midsole component for an article of footwear.

In some aspects, the article is an insert. An insert 36 can be receivedin recess 28. As illustrated in FIG. 2 , insert 36 can providecushioning or resiliency in the sole component. First portion 26 canprovide structure and support for insert 36. In such aspects, firstportion 26 can be formed of a material of higher specific gravity and/orhardness as compared to insert 36 such as, for example, non-foammaterials including rubber and thermoplastic polyurethane, as well asfoam materials. In certain aspects, insert 36 can be formed of anionomer foam as disclosed herein.

Insert 36 has a curved rear surface 38 to mate with curved rear surface32 of recess 28 and a transverse front surface 40 to mate withtransverse front surface 34 of recess 28. An upper surface 42 of insert36 is in contact with and secured to upper 12 with adhesive or othersuitable fastening means. For example, when there is an insert 36, arecess 28 can extend from heel portion 24 to forefoot portion 20. Incertain aspects, the rear surface 32 of recess 28 is curved tosubstantially follow the contour of the rear of heel portion 24 and thefront surface 34 of recess 28 extends transversely across first portion26.

As seen best in FIG. 3 , a ground engaging lower surface 44 of firstportion 26 includes a plurality of projections 46. Each projection 46 issurrounded by a groove 48. A plurality of transverse slots 50 are formedin lower surface 44, extending between adjacent projections 46. Alongitudinal slot 52 extends along lower surface 44 from heel portion 26to forefoot portion 20.

FIGS. 4 and 5 show bottom and top views of an insert 60 which can beused in a sole component as described herein. Insert 60 is similar toinsert 36, but as illustrated in FIGS. 4 and 5 , insert 60 is formed oftwo types of materials 62 and 64, where at least one of the materials isan ionomer foam as disclosed herein. FIG. 4 shows a bottom view ofinsert 60, while FIG. 5 shows a top view of insert 60 formed of twotypes of materials 62 and 64, with the insert placed inside a firstportion 66 to form a sole component 14. Inserts with more than two typesof materials, at least one of which is an ionomer foam as disclosedherein, can also be used. In the example illustrated in FIGS. 4 and 5 ,a portion of a first material 62 can be used in the heel region of theinsert, and a portion of a second material 64 can be used in the toeregion of the insert. A higher specific gravity material can be used tosupport the heel region, while a lower specific gravity material can beused to support the toe region. For example, the specific gravity of thefirst material can be at least 0.02 greater than the specific gravity ofthe second material. The shape of the portions of the two materials 62and 64 of the insert can be any suitable shape. For example, the heelregion can be in the shape of a wedge. Inserts formed of two types ofmaterials can be useful in running shoes, as well as in basketballshoes.

In some aspects, the article can be something other than a solecomponent. For example, the article can be an upper or an uppercomponent. An upper component refers to a piece that is stitched orotherwise joined with one or more other pieces to form an upper. Thematerials in the upper generally contribute to characteristics such asbreathability, conformability, weight, and suppleness or softness. Alower component refers to a piece that is joined with one or more otherpieces to form the lower portion of an article of footwear. The lowercan include, for example, the outsole and midsole. The choice of outsolematerials and design will contribute, for instance, to the durability,traction, as well as to the pressure distribution during use. Themidsole materials and design contribute to factors such as thecushioning and support. Grindery components include all of theadditional components that can be attached to the upper, lower, or both.Grindery components can include, for example, eyelets, toe puffs,shanks, nails, laces, velcro, catches, backers, linings, padding, heelbackings, heel foxings, toe caps, etc.

In some aspects, the upper is a lasted upper. A “lasted upper,” as usedherein, refers to an upper that is formed into the shoe shape prior toattachment to the sole by one or more mechanical means. The lasted uppercan include a heel counter formed to shape the heel of the upper. Thelasted upper can include a strobel or a strobel board attached to theupper, typically via a strobel stitch.

While the ionomer foams described herein can be used for making any of avariety of components, including a variety of components for an articleof footwear, in particular aspects the components include a midsole, anoutsole, an insole, or an insert. Additional articles can include atongue padding, a collar padding, and a combination thereof. Asdescribed above and detailed more completely below, the articlescomprising the ionomer foams described herein can exhibit a uniquebalance of beneficial physical properties such as high energy return,high split tear, low specific gravity, and low compression. Furthermore,the ionomer foam can also be reprocessed with minimal loss in physicalproperties (e.g., for recycling), providing a solution for materialssustainability.

In the articles comprising the ionomer foam described herein, theionomer foam portion of the article can exhibit a beneficial split tear,for example a high split tear for a sole component in an article offootwear. In some aspects, the ionomer foam can have a split tear valueof about 1.0 kilogram/centimeter (kg/cm) to 4.5 kg/cm, about 1.6 kg/cmto 4.0 kg/cm, about 2.0 kg/cm to 4.0 kg/cm, about 2.0 kg/cm to 3.5kg/cm, or about 2.5 kg/cm to 3.5 kg/cm. The split tear can be measuredpursuant to ASTM D3574-95. In some aspects, the ionomer foam isinjection molded (i.e., is not exposed to a separate compression moldingstep after being formed by injection molding and removed from theinjection mold), or is injection molded and subsequently compressionmolded in a separate compression mold having different dimensions thanthe mold used in the injection molding step. The ionomer foam can have asplit tear of about 0.08 kg/cm to 4.0 kg/cm, about 0.9 kg/cm to 3.0kg/cm, about 1.0 to 2.0 kg/cm, about 1.0 kg/cm to 1.5 kg/cm, or about 2kg/cm. In some aspects, the ionomer foam the ionomer foam is injectionmolded, and has have a split tear of about 0.07 kg/cm to 2.0 kg/cm, orabout 0.8 kg/cm to 1.5 kg/cm, or about to 1.2 kg/cm, about 1.5 kg/cm to2.2 kg/cm.

In some aspects, the ionomer foam portion of the article or component ofan article can have a stiffness of about 30 Newtons per millimeter(N/mm) to 275 N/mm, about 40 N/mm to 275 N/mm, about 40 N/mm to 100N/mm, about 100 N/mm to 200 N/mm, about 50 N/mm to 150 N/mm, about 50N/m to 100 N/mm, or about 50 N/mm to 85 N/mm. In some aspects, theionomer foam article or article component is formed by injectionmolding, or by injection molding and subsequently compression molding.The ionomer foam can have a stiffness of about 30 N/mm to 275 N/mm,about 40 N/mm to 275 N/mm, about 40 N/mm to 100 N/mm, about 100 N/mm to200 N/mm, about 50 N/mm to 150 N/mm, about 50 N/m to 100 N/mm, or about50 N/mm to 85 N/mm.

The energy return, a measure of the percentage of energy the ionomerfoam portion of the article or component returns when it is releasedafter being compressed under load, can provide improved performance forathletic shoes, e.g. for reducing energy loss or dissipation whenrunning. This is especially true for running and other athletic shoes.In some aspects, the ionomer foam portion of the articles and componentsprovided herein have an energy return of about 50% to 95%, about 60% to95%, about 60% to 90%, about 60% to 85%, about 65% to 85%, or about 70%to 85%. In some aspects, the ionomer foam is injection molded or isinjection molded and subsequently compression molded. The ionomer foamof the present disclosure can have an energy return of about 50% to 95%,about 60% to 95%, about 60% to 95% (e.g., about 60% to 85%; about 65% to80%; about 65% to 75%; about 70% to 80%; or about 75% to 80%; about 75%to 85%, about 75% to 90%, about 80% to 95%; or about 85% to 95%). Theenergy return can be measured as described in the examples below.

As discussed above, the ionomer foam of the present disclosure exhibitsa low specific gravity, which beneficially reduces the weight ofmidsoles or other components containing the ionomer foam. In someaspects, the ionomer foam, including ionomer foam present in midsolesand midsole components, can have a specific gravity of about 0.05 to0.25, about 0.05 to 0.2, about 0.05 to 0.15, about 0.08 to 0.15, about0.08 to 0.20, about 0.08 to 0.25, or about 0.1 to 0.15. In some aspectsthe ionomer foam has a specific gravity of about 0.15 to 0.3, about 0.2to 0.35, or about 0.15 to 0.25.

Several methods of measuring resiliency and/or energy return of foamsexist in the art. One method of measuring resiliency of foams is basedon ASTM D 2632-92, which is a test for solid rubber materials. For usewith foams, the test sample is prepared as described in ASTM D2632-92,but uses a sample of foam in place of the sample of solid rubber. Thistest uses a plunger which is dropped from a height onto a test samplewhile being guided by a vertical rod. The drop height is divided into100 equal parts, and the height to which the plunger rebounds ismeasured using this 100 part scale, to determine the resiliency of thesample. Alternative methods which use a ball of standard weight droppedonto a sample, and which measure the rebound height of the ball todetermine the resiliency of the sample can also be used. In someaspects, the resiliency and/or energy return are determined usingforce/displacement behavior measured using an Instron Electropuls asdescribed in the Examples. For example, an Instron Electropuls E10000with a stainless steel 45 mm circular cross section impact geometry canbe used to evaluate compression at one or more different compressioncycles. The compression cycle can include a running compression cycleconsisting of samples being compressed under displacement control from 0Newtons (N) to 300 N and back to 0 N in 180 milliseconds (ms), followedby a pause of 400 ms for a total of ˜1.7 Hertz (Hz). A walkingcompression cycle can consist of samples compressed from 0 N to 144 Nand back to 0 N in 600 ms followed by a pause of 400 ms for a total of˜1 Hz. The corresponding force-displacement data provided informationabout the foam modulus (stiffness), energy return, set, fatiguebehavior, etc. over many cycles. Energy input is taken as the integralof the force-displacement curve during compression force loading. Energyoutput is taken as the integral of the force displacement curve duringunloading. Energy return is the integral of the unloading loaddeflection curve normalized by the integral of loading load deflectioncurve (energy output)/(energy input), which can also be viewed as theenergy efficiency of the foam. Fatigue behavior is judged by changes inthe foam displacement at the max load of a cycle. All measuredproperties: stiffness, energy input, energy output, and fatigue aremeasured for thousands of cycles for both running and walkingcompression cycles.

The specific gravity of a foam is also an important physical property toconsider when using a foam for in an article of footwear or athleticequipment. The ionomer foams of the present disclosure can have aspecific gravity of from about 0.02 to about 0.22, or of from about 0.03to about 0.12, or of from about 0.04 to about 0.10, or from about 0.11to about 0.12, or from about to about 0.12, from about 0.15 to about0.2; about 0.15 to about 0.30. Alternatively or in addition, the ionomerfoam can have a specific gravity of from 0.01 to 0.10, or of from 0.02to or of from 0.03 to 0.06; 0.08 to 0.15; or from 0.10 to 0.12. Forexample, the specific gravity of the ionomer foam can be from or from0.15 to 0.2, or can be from 0.10 to 0.12 The ionomer foam can beinjection molded, or can be injection molded and subsequentlycompression molded.

In particular examples, the resiliency and/or energy return of thesubsequently compression molded ionomer foam can be at least at least 6percentage points, or at least 7 percentage points, or at least 8percentage points, or at least 9 percentage points, or at least 10percentage points, or at least 12 percentage points greater than theresiliency and/or energy return of the injection molded ionomer foamwhich has not subsequently been compression molded, when the compressionmolded ionomer foam has a resiliency and/or energy return greater than45%, or greater than 50%, or greater than 55%, or greater than 60%, orgreater than 65%, and the compression molded ionomer foam can have aspecific gravity of from 0.02 to 0.15, or of from 0.03 to 0.12, or offrom 0.04 to 0.10 or from 0.11 to 0.12, from 0.15 to 0.2; or 0.15 to0.30.

The specific gravity of the ionomer foam can be determined by testing atleast 3 representative samples taken from a foam sample (e.g., a 2inch×2 inch sample or a 1 inch×1 inch sample), or at least 3 entire foamarticles or components. Using a balance with appropriate accuracy forthe weight of the sample, the weight of each sample is determined bothin air and when the sample is completely submerged in distilled water ata temperature of 22 degrees Celsius (° C.)±2° C., after removing any airbubbles adhered to the surface of the foam sample weighing. The specificgravity (S.G.) is then calculated by taking the weight of the sample inwater and subtracting that from the weight of the sample in air, andthis value is then divided into the weight of the sample in air, whereall the weights are weights in grams.

Compression set of a foam is another important physical property for afoam used as a component of an article of footwear or athleticequipment. In accordance with the present disclosure, the ionomer foamcan have a compression set of from 40% to 100%. For example, thecompression set can be from 45% to 90%, or from 40% to 80%, or from 50%to 75%.

Compression set can be measured by preparing a sample of a standardthickness (e.g., millimeters (mm)) of a foam. Components having athickness less than the standard can be stacked to make a sample havingthe standard thickness. The sample is loaded into a metal compressionplate and compressed to a height of 50% of the original thickness (e.g.,5 mm). The sample is placed in a 50° C. oven on its side for 6 hours. Atthe end of the 6 hours, the sample is removed from the oven and from themetal compression plate, and allowed to cool for 30 minutes. Oncecooled, the thickness of the sample is measured. The percent compressionset (C.S.) is calculated by (a) subtracting the final sample thicknessfrom the original sample thickness, and (b) subtracting the 50%compressed thickness from the original sample thickness, (c) dividing(a) by (b), and (d) multiplying the result by 100 to obtain the percentcompression set (where all thicknesses are measured in millimeters).

Split tear for foams can be measured using ASTM D3574-95. Although thismethod is directed to bonded and molded urethane foams, it can be usedon ionomer foam in accordance with the present disclosure. A sample ofionomer foam having a thickness of 10 mm±1 mm. If the ionomer foam hasan outer skin, the outer skin should not be present on the test sample.A 3 cm long cut is placed in the center of one end of the specimen, andmarked in five successive 2 cm portions along the edge of the sample.The sample is tested as described in ASTM D3574-tear strength of theionomer foam can range from 4 kilograms per centimeter (kg/cm) to kg/cm.

The tensile strength of the foam is another important physicalcharacteristic. The ionomer foam can have a tensile strength of from 5kilograms per cubic centimeter (kg/cm 2) to 25 kg/cm 2, or of from 10kg/cm 2 to 23 kg/cm 2, or of from 15 kg/cm 2 to 22 kg/cm 2. The tensilestrength can be measured on a die cut sample of the foam in the shape ofa dumbbell of a standard size such as a 2.5 cm in width by 11.5 cm inlength, with a minimum thickness of 3 to 4 mm. The dumbbell follows theshape described in ASTM D412, die C. The sample is loaded symmetricallyinto and tested using a long travel extensometer such as the Instron2603-080 which allows for a minimum of 1000% strain with a gauge lengthof 25 mm and a resolution of at least 0.1 mm. The tensile value at thefailure point of the sample (the point during testing when the loadvalue initially drops) is recorded.

Another physical property to consider when determining whether or not afoam is suitable for an intended use, for example for an intended use inan article of footwear or athletic equipment, is its 300% elongation.The ionomer foam can have an elongation of at least 125 kg/cm², or atleast 150 kg/cm².

Ionic foams described herein can be made by a process/method includingreceiving a composition described herein, and physically foaming thecomposition to form an ionomer foam having a specific gravity of about0.7 or less, or 0.5 or less, or 0.4 or less, or 0.3 or less. The processcan include blowing the composition to produce an article or componentcomprising the ionomer foam. In some examples, the process for formingthe ionomer foam comprises injection molding a mixture including acomposition as described herein and a supercritical fluid (e.g.,supercritical CO₂ or supercritical N₂) in a mold, and removing theionomer foam from the mold.

In some examples, the composition can be prepared by methods known inthe art, including using a suitable twin-screw extruder. An extruder(e.g., single or twin screw) can be used to provide a composition. Theextruder can have a motor to turn a screw inside the extruder. Extrudermay be a single screw or twin screws made of individual elements ofvarious sizes and pitches appropriate for mixing or kneading thespecific materials used. In some examples, the extruder has a twinscrew.

The various components that make up the compositions used to form theionomer foam of the various examples described herein are added into theextruder through one or more port. The various components can be addedas a melt or as appropriately-sized solid particles, for example chipsor pellets, that are melted in section as they are mixed in the barrelof the extruder. The contents of the extruder can be heated to melt thecomposition. A supercritical fluid can be added into the melt as aphysical blowing agent. In particular examples, the ionomer foam isprepared by using a physical blowing agent which foams the compositionafter it exits the extruder, and the ionomer foam is thus substantiallyfree of a chemical blowing agent or decomposition product thereof.

In some examples, the compositions can be added as a melt at atemperature close to or at a temperature that causes ionic crosslinksbetween polymer chains to dissociate. At lower temperatures the ionicmoieties can reform or reassociate. Due to the ionic crosslinking, theextent to which the compositions are crosslinked during processing canbe controlled by controlling the temperature; by causing a temperaturereduction at a desired point to increase crosslinking, which results inan increase in the modulus or viscosity of the molten resin as the ionicmoieties reassociate.

If a chemical blowing agent is used, the processing (melting)temperature used can be sufficiently below the temperature that wouldtrigger the blowing agent. In order to foam the composition, thetemperature near the exit of the extruder can be increased to atemperature close to or at the triggering temperature of a chemicalblowing agent, thereby producing a chemically foamed ionomer foam as thecomposition exits the extruder (e.g., as the composition is injectedinto an injection mold).

Alternatively or in addition, a physical blowing agent can be used forfoam the composition to form a physically foamed ionomer foam, or aphysically and chemically foamed ionomer foam. For example, asupercritical fluid such as supercritical CO₂ or supercritical N₂ can bemixed with the molten polymeric composition in the barrel of theextruder. As the mixture of the molten composition comprising one ormore ionomeric copolymers and a supercritical fluid exits the extruder,the pressure drop between the higher pressure in the extruder and thelower pressure outside the extruder causes the supercritical fluid totransition to the gas phase and foam the molten polymeric composition.

In some examples, the ionomeric copolymer component of the ionomer foamcan form phase separated domains. For example, less polar or nonpolarolefinic repeat units of the ionomeric copolymer can phase separate intoprimarily olefin-rich domains. The more polar cations can phase separateinto cation-rich domains surrounded by domains rich in the acid groupsfrom the ionomeric copolymer, wherein the anionic portions in the acidgroups are ionically crosslinked by the cations.

Various examples include methods of manufacturing an article of footwearor components for an article of footwear. In some examples, the methodsof manufacturing an article of footwear include injection molding acomposition to form an ionomer foam described herein to produce a foamarticle or component of an article, such as an article of footwear. Thearticle or component of an article can be a midsole or a component of amidsole, and the method can include providing an upper and an outsolefor an article of footwear; and combining the midsole or midsolecomponent, the upper, and the outsole to make an article of footwear. Insome examples, the method of manufacturing the article of footwearincludes combining an article comprising an ionomer foam, an upper, andan outsole to make an article of footwear.

The articles or components of articles such as midsoles, midsolecomponents, inserts and insert components can be prepared by injectionmolding a melt composition described herein using a physical blowingagent. The injection molding can use a screw-type injector that allowsfor maintaining and controlling the pressure in the injector barrel. Theinjection molding machine can allow metering and delivering asupercritical fluid such as CO₂ or N₂ into the composition prior toinjection. The supercritical fluid can be mixed into the compositionwithin the injection barrel and then injected into the mold. Thesupercritical fluid can then expand to create cell nuclei to form thephysical foam within the mold. The injection molding can includephysical foaming of the compositions described herein using amicrocellular foam injection molding process, such as, for example theMUCELL process (Trexcel Inc., Royal Oak. Michigan, USA).

In some examples, the ionomer foams of the various examples describedherein are made using a process that involves impregnating a polymericcomposition (e.g., at or above a softening temperature of thecomposition) with a physical blowing agent at a first concentration orfirst pressure. As used herein, the term “impregnating” generally meansdissolving or suspending a physical blowing agent in a composition. Theimpregnated composition can then be foamed, or can be cooled (whenapplicable) and re-softened (when applicable) for blowing at a latertime.

In some instances, the impregnated composition is foamed by reducing thesolubility of the physical blowing agent in the polymer matrix throughpressure or temperature changes. The reduction in solubility of thephysical blowing agent can release additional amounts (e.g., to create asecondary expansion of an originally-formed microcell in thecomposition) of the impregnated physical blowing agent from thecomposition, to further blow the composition, forming a foam composition(e.g., a foam composition having a closed-cell structure).

In addition to injection molding, the ionomer foam of the presentdisclosure can be foamed and molded using various processes known in theart. For example, the ionomer foam can be formed into slab foam,filament or strand foams, particulate (e.g., bead) foams of variousshapes and sizes, etc. These various forms of foam can then be used indifferent ways. For example, like injection molded foam, slab foam andfilament or strand foam can be used directly as a finished foam article,or can be shaped (e.g., cut, buffed, or trimmed) to form a finished foamarticle, or can be compression molded to form a finished foam article.Optionally, the ionomer foam can be subjected to annealing processes aspart of forming the finished foam article. Pellets of the compositionscan be used to form individual particulate ionomer foams, or can befoamed and molded to form unitary molded foam articles composed ofindividual portions of foam affixed to each other.

The ionomer foams of the various examples described herein may befurther shaped or molded by any of the methods known for formingarticles from thermoplastic materials. Optionally, the ionomer foams ofthe present disclosure which have been foamed using any suitable blowingprocess (e.g., blowing using a physical and/or chemical blowing agent),including by injection molding using only a physical blowing agent, canthen be compression molded to form a compression molded foam.

In some examples, the ionomer foam of the present disclosure can beprepared by a process comprising (i) softening a composition (e.g., byheating at a first temperature at or above a softening temperature ofthe composition); (ii) simultaneously or sequentially with the softening(when applicable), contacting the composition with a first concentrationor first pressure of a physical blowing agent sufficient to drive anamount of the physical blowing agent into the composition or combine thephysical blowing agent with the composition; (iii) changing theconcentration or pressure (e.g., decreasing the pressure orconcentration) of the physical blowing agent to a second concentrationor second pressure that is effective to foam the composition, therebyforming an ionomer foam (e.g., an ionomer foam having a closed-cellstructure); and, (iv) following the changing, cooling (when applicable)the ionomer foam to (e.g., cooling to a temperature below the softeningtemperature of the composition), to form a solidified ionomer foam.

In other examples, the ionomer foam of the present disclosure isprepared by (i) contacting (e.g., dissolving or suspending) thecomposition with a first concentration of a chemical blowing agent, insome examples, at or above a softening temperature of the composition(ii) triggering the chemical blowing agent to foam the composition,thereby forming an ionomer foam (e.g., an ionomer foam having aclosed-cell structure); and, (iii) following the triggering, in someexamples, cooling the ionomer foam to, e.g., a temperature below itssoftening temperature, to form a solidified ionomer foam. In someexamples, the “triggering” of the chemical blowing agent is performed byany suitable method, including heating the composition comprising aconcentration of the chemical blowing agent to a temperature sufficientto “trigger” the chemical blowing agent, wherein the concentration ofthe chemical blowing agent is effective to foam the composition, therebyforming an ionomer foam (e.g., an ionomer foam having a closed-cellstructure).

In some examples, the contacting comprises contacting at a pressure offrom about 10 MPa to about 100 MPa (e.g., from about 30 MPa to about 100MPa, about 20 MPa to about 80 MPa, about 30 MPa to about 60 MPa or about40 MPa to about 70 MPa).

In some aspects, the present disclosure is directed to a compressionmolded ionomer foam, and to a method of forming compression moldedionomer foam for, among other applications, articles of footwear orathletic equipment. In some examples, the method can be a processcomprising providing (e.g., preparing) an ionomer foam preform and thencompression molding the ionomer foam preform to form a compressionmolded ionomer foam. For example, the ionomer foam can be compressionmolded by placing the ionomer foam preform in a compression mold havinga height less than the initial height of the ionomer foam preform andclosing the mold, thereby compressing the ionomer foam preform to theheight of the mold. Simultaneously or sequentially with the compressing,the ionomer foam preform can be heated in the closed compression mold.During the compression molding, the temperature of at least a portion ofthe ionomer foam preform in the closed mold can be raised to atemperature within ±30° C. of the softening temperature of thecomposition. The temperature can be raised by heating the closed mold.Following the raising of the temperature, while the ionomer foam preformremains closed in the compression mold, the temperature of at least aportion of the ionomer foam preform can be lowered. The temperature canbe lowered by cooling the closed mold. The lowering can lower thetemperature of at least a portion of the ionomer foam preform to atemperature at least 35° C. below the softening temperature of thecomposition, thereby forming the compression molded ionomer foam.Following the cooling, the compression mold can be opened, and thecompression molded ionomer foam can be removed from the compressionmold.

Examples contemplated herein are directed to methods of manufacturingarticles of footwear or athletic equipment. For example, the method cancomprise providing components such as midsoles and inserts of an articleof footwear in accordance with the present disclosure, and combining thecomponent with a footwear upper and an outsole to form the article offootwear.

One method of making compression molded ionomer foam articles such asmidsoles and inserts or components of articles such as components ofmidsoles or components of inserts described herein comprises forming anionomer foam preform and compression molding the ionomer foam preform tomake a compression molded ionomer foam. In some examples, the foampreforms of the various examples described herein are obtained byblowing the composition by about 150% to about 240% (e.g., from about150% to about 220%; about 150% to about 200%, about 175% to about 225%,about 180% to about 230% or about 160% to about 240%) in at least onedimension (e.g., the vertical dimension) using a blowing agent. In someexamples, the blown composition can be compression molded to about 120%to about 200% (e.g., from about 120% to about 180%; about 130% to about190%; about 150% to about 200%; or about 160% to about 190%) in at leastone dimension.

Thus for example, if the foaming of the composition is about 200%, theblown composition can be compression molded by a net 20% by compressionmolding to about 180%. In another example, if the composition is blowninto a 20 mm (height)×10 cm (width)×5 cm (depth) slab, and the slab iscompression molded in the height direction by 20%, the compressionmolded slab would have the dimensions 18 mm (height)×10 cm (width)×5 cm(depth). In some examples, the compression molding is substantiallymaintained.

In some examples, the ionomer foam is made using a process that involvesimpregnating a composition (e.g., at or above a softening temperature ofthe composition) with a physical blowing agent at a first concentrationor first pressure. The impregnated composition can then be foamed, orcan be cooled (when applicable) and re-softened (when applicable) forblowing at a later time. In some instances, the impregnated compositionis foamed by reducing the temperature or pressure, impacting thesolubility of the physical blowing agent. The reduction in solubility ofthe physical blowing agent can release additional amounts of theimpregnated physical blowing agent from the composition to further blowthe composition forming an ionomer foam (e.g., an ionomer foam having aclosed-cell structure).

In some examples, the compression molding process is conducted byheating the ionomer foam preform in a closed compression mold. Theionomer foam preform is heated to a temperature close to its softeningtemperature, to allow the foam to retain the shape of the compressionmold. For example, the foam preform can be heated to a temperaturewithin plus or minus (±) 30° C. of its softening temperature, or within±20° C. of its softening temperature, or within ±10° C. of its softeningtemperature, or within ±5° C. of its softening temperature. For example,the ionomer foam preform can be heated to a temperature of from about100° C. to about 250° C., or of from about 140° C. to about 220° C., orof from about 100° C. to about 150° C., or of from about 130° C. toabout 150° C.

The material used to form the compression mold can be any material whichcan withstand the temperatures used during the process, such as machinedmetals, including aluminum. The compression mold can be made using twopieces, such as a top and a bottom mold. Depending on the shape of thefoam component to be molded, a multiple-piece mold may be used in orderto more easily release the compression molded foam from the mold.

The injection molded ionomer foam can have a closed skin. A closed skincan also be formed by compression molding an ionomer foam preform in acompression mold. However, care should be taken during the compressionmolding not to subject the ionomer foam preform to conditions such thatmore than a desired amount of the closed cell structures of the foamcollapse. One way to avoid collapsing more than a desired amount of theclosed cell structures is to control the temperature of the ionomer foamduring the compression molding process, for example, by controlling thetemperature of the mold. For example, during the compression moldingstep, the heating of the ionomer foam preform in the compression moldcan be conducted for time of from 100 seconds to 1,000 seconds, or offrom 150 seconds to 700 seconds.

Once the ionomer foam has been heated in the compression mold at theappropriate temperature for the desired length of time to soften theionomer foam to the desired level, the softened preform is cooled, forexample, to a temperature at least 35° C. below its softeningtemperature, or at least 50° C. below its softening temperature, or atleast 80° C. below its softening temperature, to re-solidify thesoftened foam, thereby forming the compression molded foam. Once cooled,the compression molded ionomer foam is removed from the compressionmold. Following the heating, the cooling of the foam preform in thecompression mold can be conducted for a time of from 50 to 1,000seconds, or for a time of from 100 to 400 seconds.

In the ionomer foam of the present disclosure, the compositioncomprising one or more ionomeric copolymers has a foam structure with aspecific gravity of about 0.7, 0.5, 0.4, 0.3, or less. The ionomer foamhas a specific gravity of about 0.1 to about 0.22, about 0.2 to about0.35, or about 0.1 to about 0.35. The ionomer foam can be foamed usingany one of the methods described above. The ionomer foam can be includedin components of articles of footwear as described above, for example asole component as depicted in FIG. 1 .

The compositions provided herein can include one or more ionomericpolymers. The ionomeric polymers can include chain units derived fromone or more olefins and chain units derived from one or moreethylenically-unsaturated acid groups. The compositions can also includea plurality of cations ionically crosslink anionic form of the acidgroups in the ionomeric copolymers. In some aspects, the compositionsare essentially just the ionomeric copolymers and metal cations. Theionomeric copolymers can have a melt flow index of about 30 or less,about 20 or less, about 15 or less, about 10 or less, or about 5 orless.

A variety of ionomeric copolymers can be processed as described hereinto have a foam structure. In some aspects, the ionomeric copolymers areterpolymers of ethylene, acrylic acid, and methyl acrylate or butylacrylate. In some aspects, a ratio III of a total parts by weight of theacrylic acid in the ionomeric copolymers to a total weight of theionomeric copolymers is about 0.05 to about 0.6, about 0.1 to about 0.6,about 0.1 to about 0.5, about 0.15 to about 0.5, or about 0.2 to about0.5.

In some aspects, the ionomeric copolymers have a plurality of a firstrepeat unit having a formula according to Formula I and a plurality of asecond repeat unit having a formula according to Formula II, and aplurality of cations, wherein each of the cations is crosslinking two ormore of the second repeat units.

Each occurrence of R¹ can be independently none, a substituted orunsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl, or a substitutedor unsubstituted C₂, C₃, C₄, C₅, C₈, C₇, or C₈ alkenyl. In some aspects,each occurrence of R¹ is none.

Each occurrence of R² can be independently hydrogen, a halogen, asubstituted or unsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl, asubstituted or unsubstituted C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkenyl, asubstituted or unsubstituted phenyl, a substituted or unsubstitutedalkyl-phenyl, a substituted or unsubstituted C₁, C₂, C₃, C₄, C⁵, C₆, C₇,or C₈ alkoxy, or a substituted or unsubstituted C₃, C₄, C⁵, C₆, C₇, orC₈, C₉, C₁₀, C₁₁, or C₁₂ alkyl ester. In some aspects, each occurrenceof R² is independently a hydrogen, methyl, phenyl, or halogen. In someaspects, each occurrence of R² is

where each occurrence of R⁴ is independently a hydrogen, a substitutedor unsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl.

Each occurrence of R³ can be independently hydrogen, a substituted orunsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl, or a substitutedor unsubstituted C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkenyl. In some aspects,each occurrence of R³ is independently a hydrogen or methyl.

Each occurrence of R⁵ can be independently a hydrogen, a halogen, asubstituted or unsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl, asubstituted or unsubstituted C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkenyl, asubstituted or unsubstituted phenyl, a substituted or unsubstitutedalkyl-phenyl, a substituted or unsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇,or C₈ alkoxy, or a substituted or unsubstituted C₃, C₄, C₅, C₆, C₇, orC₈, C₉, C₁₀, C₁₁, or C₁₂ alkyl ester. In some aspects, each occurrenceof R⁵ is independently a hydrogen or a methyl.

Each occurrence of R⁶ can be independently none, a substituted orunsubstituted C₁, C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkyl, a substituted orunsubstituted C₂, C₃, C₄, C₅, C₆, C₇, or C₈ alkenyl, a substituted orunsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, or asubstituted or unsubstituted C₁-C₈ alkoxy. In some aspects, eachoccurrence of R⁶ is none.

Each occurrence of R⁷ can be independently a carboxylate, a sulfate, asulfonate, a nitrate, a phosphate, a phosphonate, or another negativelycharged functional group. In some aspects, each occurrence of R⁷ is acarboxylate. For example, in some aspects, the second repeat unit has aformula according to Formula IIA, where R⁵ and R⁶ are as descried above.

The compositions can include a plurality of cations ionicallycrosslinking the ionomeric copolymers. For example, the cations canionically crosslink anionic groups from acid groups. In some aspects,the cations ionically crosslink units having a structure according toFormula II.

In the compositions described herein, a plurality of cations are presentto crosslink negatively charged groups in the ionomeric copolymer. Forexample, an ionomer having free carboxylate groups can be crosslinked bya plurality of cations. Because the compositions are crosslinked viaionic crosslinking, the compositions are in some aspects free orsubstantially free of any covalent and irreversible chemical crosslinks,for example the compositions can be free of covalent crosslinkingbetween the ionomeric copolymers. The cations can include cations ofalkali metals or alkali earth metals such as a magnesium ion, a sodiumion, a potassium ion, a cesium ion, a calcium ion, a barium ion, amanganese ion, a copper ion, a zinc ion, a tin ion, a lithium ion, and apositively charged compound thereof. In some aspects, the cation is asodium cation, a lithium cation, a zinc cation, a magnesium cation, orany combination thereof. The cations can include organic cations such asan ammonium ion, a pyridinium ion, a guanidinium ion, an imidazoliumion, a phosphonium ion, or a sulfonium ion.

In some aspects, a ratio II of a total parts by weight of the carboxylicacid groups in the ionomeric copolymers to a total weight of theionomeric copolymers is about 0.05 to about 0.7, about 0.1 to about 0.6,about 0.2 to about 0.6, or about 0.2 to about 0.5. In some aspects, aratio II of a total parts by weight of the second repeat units in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.1 to about 0.7, about 0.1 to about 0.6, about 0.2 to about 0.6,or about 0.2 to about 0.5.

In some aspects, the composition further includes one or more additionalcomponents such as fillers, nucleating agents, or both.

Nucleating agents are widely used to modify the properties of variouspolymers. Nucleating agents can aid in decreasing foam specific gravity,increasing the number of cells present in the foam, and decreasing cellsize in the foam by providing a surface for heterogeneous nucleation ofgas bubbles from the supercritical fluid state. For the ionomer foams ofthe present disclosure, nucleating agents can influence the propertiesof the final foam article by modifying the quantity, distribution andrate of supercritical fluid conversion from a liquid to a gas during thefoaming process as lower pressures. The addition of nucleating agentsprovides a surface on which the supercritical fluid can be transformedfrom a liquid to a gas. As a consequence, many nucleation sites willresult in many gas cell domains. In a particular example, the nucleatingagent can include a metal salt of a fatty acid. In some aspects, thenucleating agent is zinc stearate. In some aspects, the compositioncontains about 0.1 weight percent (wt. %) to about 10 wt. %, about 0.1wt. % to about 5 wt. %, about 0.1 wt. % to about 2 wt. %, or about 0.5wt. % to about 2 wt. % of the nucleating agent based upon a total weightof the composition.

In some examples, the composition can also include a nanofiller.Nanofillers can not only serve as mechanical reinforcement but alsonucleating agents. A variety of nanofillers can be used in lieu of or inaddition to the zinc stearate. Nanofillers can include nanomaterialshaving one-dimensional structures such as of plates, laminas and/orshells; two-dimensional structures such as nanotubes and nanofibreshaving a diameter lower than 0.1 μm; or three-dimensional nanostructuressuch as nanoparticles or beads. Nanoplate fillers can be natural orsynthetic clays, as well as phosphates of transition metals. Clay-basednanocomposites generate an overall improvement in physical performances.The most widely used ones are the phyllosilicates. Nanofillers caninclude nano-oxides such as nanoparticles of Titanium dioxide or Rutile.Other nanofillers can include nanoparticles of alumina or aluminumoxide, diatomite, and nanoscale carbon materials such as single-wallcarbon nanotubes (SWCNT) or double-wall carbon nanotubes (DWCNT).

In some aspects, the compositions further include one or more olefinicpolymers. Olefinic polymers can include ethylene-based copolymers,propylene-based copolymers, and butene-based copolymers. In someaspects, the olefinic polymer is an ethylene-based copolymer such as astyrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; any copolymer thereof, andany blend thereof. In some aspects, a ratio V of a total parts by weightof the olefinic polymers present in the composition to a total parts byweight of the ionomeric copolymers in the composition is about 0.0 toabout 0.6, about 0.0 to about 0.4, about 0.01 to about 0.4, or about toabout 0.6, or about 0.1 to about 0.4.

In some aspects, the compositions include an ethylene-vinyl acetate(EVA) copolymer. The ethylene-vinyl acetate (EVA) copolymer can have arange of vinyl acetate contents, for example about 50% to about 90%,about 50% to about 80%, about 5% to about 50%, about 10% to about 45%,about 10% to about 30%, about 30% to about 45%, or about 20% to about35%.

Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. It will be further understoodthat terms, such as those defined in commonly used dictionaries, shouldbe interpreted as having a meaning that is consistent with their meaningin the context of the specification and relevant art and should not beinterpreted in an idealized or overly formal sense unless expresslydefined herein.

It should be noted that ratios, concentrations, amounts, and othernumerical data can be expressed herein in a range format. Where thestated range includes one or both of the limits, ranges excluding eitheror both of those included limits are also included in the disclosure,e.g. the phrase “x to y” includes the range from ‘x’ to ‘y’ as well asthe range greater than ‘x’ and less than ‘y’. The range can also beexpressed as an upper limit, e.g. ‘about x, y, z, or less’ and should beinterpreted to include the specific ranges of ‘about x’, ‘about y’, and‘about z’ as well as the ranges of ‘less than x’, less than y′, and‘less than z’. Likewise, the phrase ‘about x, y, z, or greater’ shouldbe interpreted to include the specific ranges of ‘about x’, ‘about y’,and ‘about z’ as well as the ranges of ‘greater than x’, greater thany′, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”,where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about‘y’”. It is to be understood that such a range format is used forconvenience and brevity, and thus, should be interpreted in a flexiblemanner to include not only the numerical values explicitly recited asthe limits of the range, but also to include all the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. To illustrate, anumerical range of “about 0.1% to 5%” should be interpreted to includenot only the explicitly recited values of about 0.1% to about 5%, butalso include individual values (e.g., 1%, 2%, 3%, and 4%) and thesub-ranges (e.g., 0.5%, 1.1%, 2.4%, 3.2%, and 4.4%) within the indicatedrange.

The terms “about” and “substantially” are used herein with respect tomeasurable values and ranges due to expected variations known to thoseskilled in the art (e.g., limitations and variabilities inmeasurements).

As used herein, the term “units” can be used to refer to individual(co)monomer units such that, for example, styrenic repeat units refersto individual styrene (co)monomer units in the polymer. In addition, theterm “units” can be used to refer to polymeric block units such that,for example, “styrene repeating units” can also refer to polystyreneblocks; “units of polyethylene” refers to block units of polyethylene;“units of polypropylene” refers to block units of polypropylene; “unitsof polybutylene” refers to block units of polybutylene, and so on. Suchuse will be clear from the context.

The term “copolymer” refers to a polymer having two or more monomerspecies, and includes terpolymers (i.e., copolymers having three monomerspecies).

Reference to “a” chemical compound refers one or more molecules of thechemical compound, rather than being limited to a single molecule of thechemical compound. Furthermore, the one or more molecules may or may notbe identical, so long as they fall under the category of the chemicalcompound. Thus, for example, “a” polyamide is interpreted to include oneor more polymer molecules of the polyamide, where the polymer moleculesmay or may not be identical (e.g., different molecular weights and/orisomers).

Unless otherwise specified, temperatures referred to herein are based onatmospheric pressure (i.e. one atmosphere).

Before proceeding to the Examples, it is to be understood that thisdisclosure is not limited to particular aspects described, and as suchmay, of course, vary. Other systems, methods, features, and advantagesof foam compositions and components thereof will be or become apparentto one with skill in the art upon examination of the following drawingsand detailed description. It is intended that all such additionalsystems, methods, features, and advantages be included within thisdescription, be within the scope of the present disclosure, and beprotected by the accompanying claims. It is also to be understood thatthe terminology used herein is for the purpose of describing particularaspects only, and is not intended to be limiting. The skilled artisanwill recognize many variants and adaptations of the aspects describedherein. These variants and adaptations are intended to be included inthe teachings of this disclosure and to be encompassed by the claimsherein.

Examples

Now having described the aspects of the present disclosure, in general,the following Examples describe some additional aspects of the presentdisclosure. While aspects of the present disclosure are described inconnection with the following examples and the corresponding text andfigures, there is no intent to limit aspects of the present disclosureto this description. On the contrary, the intent is to cover allalternatives, modifications, and equivalents included within the spiritand scope of the present disclosure.

Materials

SURLYN 9320, HPF AD1035, HPF2000, SURLYN 8150, SURLYN 8320, and HPFAD1172 were obtained from DuPont (Wilmington, Delaware, USA). SURLYN9320 is a zinc ionomer of ethylene acid acrylate terpolymer. HPF AD1035,HPF AD1172, and HPF2000 are magnesium ionomers of ethylene acid acrylateterpolymer. SURLYN 8150 is a sodium ionomer of ethylene acid copolymer.SURLYN 8320 is a sodium ionomer of ethylene acid acrylate terpolymer.

Solid and Foam Polymer Characterization

Solid

Dynamic scanning calorimetry (DSC) was performed on a TA instrumentsQ2000. 10-30 mg pieces of undried resin pellets were cycled from −90° C.to 225° C. at 20 degrees Celsius per minute (° C./min) and cooled to−90° C. at 10° C./min. Each material was run in duplicate The T_(m) andT_(g) values were recorded from the second cycle.

Dynamic mechanical analysis (DMA) was performed on a TA instruments Q800(New Castle, Delaware, USA). Solid 150 mm×100 mm×2 mm (L×W×H) plaques ofeach material were injected molded. From the injection molded plaquesapproximately 10 mm×60 mm×2 mm (L×W×H) samples were die cut. Strain andfrequency sweeps experiments were run at 25° C. Strain sweep experimentssampled the range from 2×10⁻⁴ to 2% strain at 1 Hz. Frequencies from to100 Hz were sampled with 10 points per decade for the frequency sweepexperiments at % strain. Temperature sweep experiments were conducted byscanning from −20° C. to 100° C. at 5° C./min with 0.1% strain at 1 Hz.The glass transition temperature, T_(g), was recorded at the peak of theloss modulus, G′. If there is not a peak in G″ the peak of tan δ wasrecorded as the T_(g). Values for G′, G″, and tan δ were recorded at 25°C.

Viscosity measurements were collected on a TA instruments DHR-3Rheometer using flat parallel plates. Samples of 25 mm circular crosssection and circle roughly 2 mm thick were die cut from a solidinjection molded plaque. The samples were dried before placing in therheometer. All samples were equilibrated at 180° C. for 2-5 minutes andtrimmed to obtain a final gap of <1 mm. A flow sweep experiment withshear rates from 0.01 to 100 reciprocal seconds (s⁻¹) was conducted. Thedata was fit with Carreau, Carreau-Yasuda, and Williamson models and thebest-fit was selected to record the zero-shear viscosity value.

Foam

The specific gravity (SG) of 10-20 mm foamed plaques was measured usinga Densicom Tester (Qualitest, Plantation, Florida, USA). Pre-weighedsamples were submerged in a water bath and the ratio of the mass of thesample in air and the mass of the sample in water was used to calculatethe specific gravity of the sample.

Water uptake. foamed samples were dried in a vacuum oven at 50° C. for 2days before being submerged in a water bath for 24 h. The surface waterwas removed by gently blotting it from the surface of the sample beforeweighing. The water uptake was calculated as the percent mass differencebetween the dry and wet samples.

Force/displacement behavior for the foams and the foamed articles wasmeasured using an Instron Electropuls E10000 (Instron, Norwood,Massachusetts, USA) with a stainless steel circular cross section impactgeometry. Most foam slabs were approximately 10 mm, some were thinner orthicker. Each sample was evaluated by two different compression cycles:“running” and “walking”. A “running” compression cycle consists ofsamples being compressed under displacement control from ON to 300N andback to ON in 180 ms, followed by a pause of 400 ms for a total of ˜1.7Hz. The “walking” compression cycle consist of samples compressed fromON to 144N and back to ON in 600 ms followed by a pause of 400 ms for atotal of ˜1 Hz. The corresponding force-displacement data providedinformation about the foam modulus (stiffness), energy input, energyoutput, set, fatigue behavior, etc., over many cycles. Typicalcharacterization using the compression sequence above are run for 5000cycles, which simulates approximately ˜5-10 miles of walking/running andtakes about 45 minutes of testing time on the Electropuls. Longer runsup to 100,000 compression cycles are done to simulate acceleratedmaterials response to ˜100-200 miles of use.

Energy input is taken as the integral of the force-displacement curveduring compression force loading. Energy output is taken as the integralof the force displacement curve during unloading. Energy return is theintegral of the unloading load deflection curve normalized by theintegral of loading load deflection curve (energy output)/(energyinput), which can also be viewed as the energy efficiency of the foam.Fatigue behavior is judged by changes in the foam displacement at themax load of a cycle. All measured properties: stiffness, hysteresis, andfatigue are measured for thousands of cycles for both running andwalking compression cycles.

Solid and Foam Injection Molding of Virgin and Reprocessed Polymer.

Dried virgin or reprocessed polymer pellets were fed into the hopper ofan Arburg 320C injection molding machine equipped with a MUCELL system.The MUCELL system injects supercritical fluid into the polymer melt tocreate a final article that is physically foamed. That is, foams werecreated only using the resin, supercritical fluid, and injectionmachine. Nitrogen (N₂) was used predominantly and lead to moreconsistent samples, but Carbon Dioxide (CO₂) was also demonstrated towork successfully to yield physically foamed samples. Solid plaques aremade without utilizing the MUCELL process. That is, using conventionalinjection molding.

-   -   Machine: Arburg 320C with 30 mm screw    -   Supercritical Fluids used: carbon dioxide (CO₂) or nitrogen (N2)    -   Rectangular Mold Geometry: 4″×6″ with variable thickness of 2*,        5, 10, 15 or 20 mm. *(2 mm was solid resin, others were foamed)    -   Shot size (resin mass): varied, but typically 60-80 g    -   Temperatures:        -   1) Hopper/feed zone temperature: 40C        -   2) Barrel Zone 1: 177-210C        -   3) Barrel Zone 2: 177-210C        -   4) Barrel Zone 3: 190-220C        -   5) Barrel Zone 4: 190-220C        -   6) Nozzle temperature: 190-220C        -   7) Mold temperature: 29-49C (but worked better at higher            temps to form thinner skins, but lead to longer cycling            time)    -   Injection speed: 0.7-0.8 in/sec, or a related moderate feed rate    -   Cooling time in mold: 200-400s (depending on part width or        thickness)    -   N₂ MUCELL Settings        -   Supercritical fluid: N₂        -   Feed pressure: 2500 psi        -   Flowrate: 0.4 lb/hr        -   Calculated weight percent (wt %) of N₂: 0.1%-0.3%        -   N₂ injection time: 1.7 sec (for 0.1% N₂) and 5.1 sec (for            0.3% N₂)    -   CO₂ MUCELL Settings:        -   1) Supercritical fluid: CO₂        -   2) Calculated weight percent (wt %) of CO₂: 1%-3%    -   Pressure drop: <250 psi

Twin Screw Compounding of Foams

Foam plaques, sprue, and runner pieces of 8320 and HPF2000 were milledin a mechanical grinding process to form moderately fine particulates.The ground polymer particulates were added to the feeder and extruded attemperatures >190° C. Extrudated strands were cooled via waterbath andpelletized with a knife chopper.

The initial extruded pellets were quite small. The small pellets werere-extruded to obtain larger pellets. That is the materials saw two heathistories. The twice extruded pellets were then injection molded withthe MUCELL process using identical injection molding process conditionsas the virgin resin to create physical foam plaques for evaluation.

Exemplary Data of Foam Plaques

A variety of foam plaques were prepared as described above using eithercompletely virgin resin or including some recycled material prepared asdescribed above. Exemplary data is presented in Table 1.

TABLE 1 Properties of Foam Plaques Article # Article #1 Article #2Article #3 Article #4 Article #5 Article #6 Article #7 Article #8Article #9 Resin 9320 9320 AD1035 HPF2000 HPF2000 8150 8320 8320 AD1172SuperCriticalFluid CO₂ N₂ CO₂ CO₂ N₂ N₂ CO₂ N₂ N₂ Weight 67.2 69.4279.88 71.07 81.84 74.47 84.76 79.57 68.94 Specific gravity 0.45 0.230.27 0.24 0.27 0.5 0.38 0.27 0.23 Energy Return (%) 82 68 83 87 87 59 6185 Stiffness (N/mm) 211 60 110 104 248 1969 66 102 74 Article # Article#10 Article #11 Article #12 Article #13 Article #14 Article #15 ResinHPF2000 HPF2000 8320 Reprocessed AD1172 + AD1035 + HPF2000 + ReprocessedEVA40L^(a) EVA40L^(a) EVA40L^(a) SuperCriticalFluid N₂ N₂ N₂ N₂ N₂ N₂Weight 71.47 61.15 63.01 83.98 83.21 78.12 Specific gravity 0.24 0.20.21 0.28 0.28 0.35 Energy Return (%) 84 86 57 75 76 78 Stiffness (N/mm)124 162 65 84 74 210 Article # Article #16 Article #17 Article #18Article #19 Resin AD1172 + AD1035 + AD1172 + AD1035 EVA2288^(b)EVA40L^(a) EVA2288^(a) SuperCriticalFluid N₂ N₂ N₂ N₂ Weight 69.81 71.6370.8 66.19 Specific gravity 0.31 0.32 0.31 0.22 Energy Return (%) 77 7779 84 Stiffness (N/mm) 125 125 144 74 ^(a)The resin is a blend of 80%ionomer and 20% EVA. ^(a)The resin is a blend of 80% wt ionomer and 20%wt EVA that were melt compounded together on a twin screw extruder^(b)The resin is a blend of 80% wt % ionomer and 20% wt % EVA that weremelt compounded together on a twin screw extruder

It should be emphasized that the above-described aspects of the presentdisclosure are merely possible examples of implementations, and are setforth only for a clear understanding of the principles of thedisclosure. Many variations and modifications may be made to theabove-described aspects of the disclosure without departingsubstantially from the spirit and principles of the disclosure. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure.

The present disclosure will be better understood upon review of thefollowing features, which should not be confused with the claims.

Feature 1. An article comprising a composition, wherein the compositioncomprises one or more ionomeric copolymers, wherein each of the one ormore ionomeric copolymers includes chain units derived from one or moreolefins and chain units derived from one or moreethylenically-unsaturated acid groups; and a plurality of cations,wherein the cations ionically crosslink anionic groups from the acidgroups in the ionomeric copolymers; wherein the composition has a foamstructure having a specific gravity of less than 0.7.

Feature 2. The article according to Feature 1, wherein the compositionfurther comprises a nucleating agent.

Feature 3. The article according to any one of Features 1-2, wherein thenucleating agent comprises a metal salt of a fatty acid.

Feature 4. The article according to any one of Features 1-3, wherein thenucleating agent comprises zinc stearate, or a variety of otheringredients . . . see Kato's responses in her version.

Feature 5. The article according to any one of Features 1-4, wherein thecomposition comprises from about 0.1 wt. % to about 2 wt. % of thenucleating agent based upon a total weight of the composition.

Feature 6. The article according to any one of Features 1-5, wherein theionomeric copolymers are terpolymers of ethylene, methyl acrylate, andacrylic acid.

Feature 7. The article according to any one of Features 1-6, wherein aratio II of a total parts by weight of the carboxylic acid groups in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.05 to about 0.6, or about 0.1-0.5.

Feature 8. The article according to any one of Features 1-7, wherein theionomeric copolymers are copolymers of ethylene, acrylic acid, and anacrylate.

Feature 9. The article according to any one of Features 1-8, wherein aratio III of a total parts by weight of the acrylic acid in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.05 to about 0.6.

Feature 10 The article according to any one of Features 1-9, wherein theacrylate is methyl acrylate or butyl acrylate.

Feature 11. The article according to any one of Features 1-10, wherein aratio IV of a total parts by weight of the methyl acrylic acid in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 5% to about 20%.

Feature 12. The article according to any one of Features 1-11, whereinthe composition further comprises one or more olefinic polymers.

Feature 13. The article according to any one of Features 1-12, whereineach of the one or more olefinic polymers is independently selected fromthe group consisting of an ethylene-based copolymer, a propylene-basedcopolymer, and a butene-based copolymer.

Feature 14. The article according to any one of Features 1-13, whereinat least one of the one or more olefinic polymers is an ethylene-basedcopolymer.

Feature 15. The article according to any one of Features 1-14, whereinthe ethylene-based copolymer is selected from the group consisting of astyrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 16. The article according to any one of Features 1-15, whereinthe ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 17. The article according to any one of Features 1-16, whereinthe ethylene-vinyl acetate (EVA) copolymer has a vinyl acetate contentof about 5% to about 50%, about 10% to about 45%, or about 20% to about30%.

Feature 18. The article according to any one of Features 1-17, wherein aratio V of a total parts by weight of the olefinic polymers present inthe composition to a total parts by weight of the ionomeric copolymersin the composition is about 0.0 to about 0.6, about 0.0 to about 0.4,about 0.01 to about 0.4, or about 0.01 to about 0.6.

Feature 19. The article according to any one of Features 1-18, whereinthe ratio V is about 0.1 to about 0.4.

Feature 20. An article comprising a composition, wherein the compositioncomprises a plurality of ionomeric copolymers, wherein each of theionomeric copolymers comprises a plurality of a first repeat unit havinga formula according to Formula I and a plurality of a second repeat unithaving a formula according to Formula II, and a plurality of cations,wherein each of the cations is crosslinking two or more of the secondrepeat units; wherein each occurrence of R¹ is independently none, asubstituted or unsubstituted C₁-C₈ alkyl, or a substituted orunsubstituted C₂-C₈ alkenyl; wherein each occurrence of R² isindependently hydrogen, a halogen, a substituted or unsubstituted C₁-C₈alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substituted orunsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, asubstituted or unsubstituted C₁-C₈ alkoxy, or a substituted orunsubstituted C₃-C₁₂ alkyl ester; wherein each occurrence of R³ isindependently hydrogen, a substituted or unsubstituted C₁-C₈ alkyl, or asubstituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence ofR⁵ is independently a hydrogen, a halogen, a substituted orunsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl,a substituted or unsubstituted phenyl, a substituted or unsubstitutedalkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy, or asubstituted or unsubstituted C₃-C₁₂ alkyl ester; wherein each occurrenceof R⁶ is independently none, a substituted or unsubstituted C₁-C₈ alkyl,a substituted or unsubstituted C₂-C₈ alkenyl, a substituted orunsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, or asubstituted or unsubstituted C₁-C₈ alkoxy; wherein each occurrence of R⁷is independently a carboxylate, a sulfate, a sulfonate, a nitrate, aphosphate, a phosphonate, or another negatively charged functionalgroup; and wherein the composition is a foam having a specific gravityof less than 0.7.

Feature 21. The article according to Feature 20, wherein the secondrepeat unit has a formula according to Formula IIA

Feature 22. The article according to any one of Features 20-21, whereinthe composition consists essentially of the plurality of ionomericcopolymers and metal cations.

Feature 23. The article according to any one of Features 20-22, whereineach occurrence of R¹ is none.

Feature 24. The article according to any one of Features 20-23, whereineach occurrence of R² is independently a hydrogen, methyl, phenyl, orchloride.

Feature 25. The article according to any one of Features 20-24, whereineach occurrence of R² is

where each occurrence of R⁴ is independently a hydrogen, a substitutedor unsubstituted C₁-C₈ alkyl.

Feature 26. The article according to any one of Features 20-25, whereineach occurrence of R³ is independently a hydrogen or methyl.

Feature 27. The article according to any one of Features 20-26, whereineach occurrence of R⁵ is independently a hydrogen or a methyl.

Feature 28. The article according to any one of Features 20-27, whereineach occurrence of R⁶ is none.

Feature 29. The article according to any one of Features 20-28, whereineach occurrence of R⁷ is a carboxylate.

Feature 30. The article according to any one of Features 20-29, whereina ratio II of a total parts by weight of the second repeat unit to atotal weight of the ionomeric copolymers is about 0.1 to about 0.6.

Feature 31. The article according to any one of Features 20-30, furthercomprising a plurality of olefinic polymers.

Feature 32. The article according to any one of Features 20-31, whereineach of the olefinic polymers is independently selected from the groupconsisting of an ethylene-based copolymer, a propylene-based copolymer,and a butene-based copolymer.

Feature 33. The article according to any one of Features 20-32, whereineach of the olefinic polymers is an ethylene-based copolymer.

Feature 34. The article according to any one of Features 20-33, whereinthe ethylene-based copolymer is selected from the group consisting of astyrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 35. The article according to any one of Features 20-34, whereinthe ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 36. The article according any one of Features 20-35, wherein theethylene-vinyl acetate (EVA) copolymer has a vinyl acetate content ofabout 10% to about 45%.

Feature 37. The article according to any one of Features 20-36, whereina ratio V of a total parts by weight of the olefinic polymers present inthe composition to a total parts by weight of the ionomeric copolymersin the composition is about 0.0 to about 0.6, about 0.0 to about 0.4,about 0.01 to about 0.4, or about 0.01 to about 0.6.

Feature 38. The article according to any one of Features 20-37, whereinthe ratio V is about 0.1 to about 0.4.

Feature 39. The article according to any one of Features 1-38, whereineach of the plurality of cations is a metal cation.

Feature 40. The article according to any one of Features 1-39, whereineach of the metal cations is independently selected from the groupconsisting of a magnesium ion, a sodium ion, a potassium ion, a cesiumion, a calcium ion, a barium ion, a manganese ion, a copper ion, a zincion, a tin ion, a lithium ion, an alkali metal, alkali earth metal, or apositively charged compound thereof.

Feature 41. The article according to any one of Features 1-40, whereineach of the plurality of cations is independently selected from thegroup consisting of a sodium cation, a lithium cation, a zinc cation, amagnesium cation, and any combination thereof.

Feature 42. The article according to any one of Features 1-41, whereinthe plurality of cations comprise magnesium cations, zinc cations,sodium cations, and any combination thereof.

Feature 43. The article according to any one of Features 1-42, whereineach of the plurality of cations is an organic cation.

Feature 44. The article according to any one of Features 1-43, whereineach of the organic cations is independently selected from the groupconsisting of an ammonium ion, a pyridinium ion, a guanidinium ion, animidazolium ion, a phosphonium ion, and a sulfonium ion.

Feature 45. The article according to any one of Features 1-44, whereinthe plurality of ionomeric copolymers have a melt flow index of about 30or less, about 20 or less, about 15 or less, about 10 or less, or about5 or less.

Feature 46. The article according to any one of Features 1-45, whereinthe plurality of olefinic polymers have a melt flow index of about0.25-5 or about 0.5-2.5

Feature 47. The article according to any one of Features 1-46, whereinthe composition has a specific gravity of about 0.2 to about 0.35.

Feature 48. The article according to any one of Features 1-47, whereinthe composition has a specific gravity of about 0.1 to about 0.22.

Feature 49. The article according to any one of Features 1-48, whereinthe composition has an energy return of about 50% to about 95%, about60% to about 95%, or about 60% to about 90%.

Feature 50. The article according to any one of Features 1-49, whereinthe composition has an energy return of about 75% to about 90%.

Feature 51. The article according to any one of Features 1-50, whereinthe composition has a stiffness of about 30 N/mm to about 275 N/mm,about 40 N/mm to about 275 N/mm, or about 40 N/mm to about 100 N/mm.

Feature 52. The article according to any one of Features 1-51, whereinthe composition has a stiffness of about 50 N/mm to about 85 N/mm.

Feature 53. The article according to any one of Features 1-52, whereinthe composition is substantially free of a chemical blowing agent ordecomposition product thereof.

Feature 54. The article according to any one of Features 1-53, whereinthe composition is substantially free of covalent crosslinks between theionomers.

Feature 55. A method of making an article, the method comprisingreceiving a composition comprising one or more ionomeric copolymers,wherein each of the one or more ionomeric copolymers includes chainunits of one or more olefins and one or more acid groups; and aplurality of cations, wherein the cations ionically crosslink anionicgroups in the ionomeric copolymers; and physically foaming thecomposition, forming a foam having a specific gravity of less than 0.7.

Feature 56. The method according to Feature 55, wherein the compositionfurther comprises a nucleating agent.

Feature 57. The method according to any one of Features 55-56, whereinthe nucleating agent comprises a metal salt of a fatty acid.

Feature 58. The method according to any one of Features 55-57, whereinthe nucleating agent comprises zinc stearate or other nucleating agentsdescribed herein.

Feature 59. The method according to any one of Features 55-58, whereinthe composition comprises from about 0.1 wt. % to about 10 wt. %, about0.1 wt. % to about 5 wt. %, about 0.1 wt. % to about 2 wt. %, or about0.5 wt. % to about 2 wt. % of the nucleating agent based upon a totalweight of the composition.

Feature 60. The method according to any one of Features 55-59, whereinthe ionomeric copolymers are terpolymers of ethylene, methyl acrylate,and acrylic acid.

Feature 61. The method according any one of Features 55-60, wherein aratio II of a total parts by weight of the carboxylic acids in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.1 to about 0.6.

Feature 62. The method according to any one of Features 55-61, whereinthe ionomeric copolymers are copolymers of ethylene and acrylic acid.

Feature 63. The method according to any one of Features 55-62, wherein aratio III of a total parts by weight of the acrylic acid in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.05 to about 0.6.

Feature 64 The method according to any one of Features 55-63, whereinthe ionomeric copolymers are copolymers of ethylene and methyl acrylicacid.

Feature 65. The method according to any one of Features 55-64, wherein aratio IV of a total parts by weight of the methyl acrylic acid in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 5% to about 20%.

Feature 66. The method according to any one of Features 55-65, whereinthe composition further comprises one or more olefinic polymers.

Feature 67. The method according to any one of Features 55-66, whereineach of the one or more olefinic polymers is independently selected fromthe group consisting of an ethylene-based copolymer, a propylene-basedcopolymer, and a butene-based copolymer.

Feature 68. The method according to any one of Features 55-67, whereinat least one of the one or more olefinic polymers is an ethylene-basedcopolymer.

Feature 69. The method according to any one of Features 55-68, whereinthe ethylene-based copolymer is selected from the group consisting of astyrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 70. The method according to any one of Features 55-69, whereinthe ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 71. The method according to any one of Features 55-70, whereinthe ethylene-vinyl acetate (EVA) copolymer has a vinyl acetate contentof about 10% to about 45%.

Feature 72. The method according to any one of Features 55-71, wherein aratio V of a total parts by weight of the olefinic polymers present inthe composition to a total parts by weight of the ionomeric copolymersin the composition is about 0.0 to about 0.6, about 0.0 to about 0.4,about 0.01 to about 0.4, or about 0.01 to about 0.6.

Feature 73. The method according to any one of Features 55-72, whereinthe ratio V is about 0.1 to 0.4.

Feature 74. A method of making an article, the method comprisingreceiving a composition comprising a plurality of ionomeric copolymers,wherein each of the ionomeric copolymers comprises a plurality of afirst repeat unit having a formula according to Formula I and aplurality of a second repeat unit having a formula according to FormulaII, and a plurality of cations, wherein each of the cations iscrosslinking two or more of the second repeat units; wherein eachoccurrence of R¹ is independently none, a substituted or unsubstitutedC₁-C₈ alkyl, or a substituted or unsubstituted C₂-C₈ alkenyl; whereineach occurrence of R² is independently hydrogen, a halogen, asubstituted or unsubstituted C₁-C₈ alkyl, a substituted or unsubstitutedC₂-C₈ alkenyl, a substituted or unsubstituted phenyl, a substituted orunsubstituted alkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy,or a substituted or unsubstituted C₃-C₁₂ alkyl ester; wherein eachoccurrence of R³ is independently hydrogen, a substituted orunsubstituted C₁-C₈ alkyl, or a substituted or unsubstituted C₂-C₈alkenyl; wherein each occurrence of R⁵ is independently a hydrogen, ahalogen, a substituted or unsubstituted C₁-C₈ alkyl, a substituted orunsubstituted C₂-C₈ alkenyl, a substituted or unsubstituted phenyl, asubstituted or unsubstituted alkyl-phenyl, a substituted orunsubstituted C₁-C₈ alkoxy, or a substituted or unsubstituted C₃-C₁₂alkyl ester; wherein each occurrence of R⁶ is independently none, asubstituted or unsubstituted C₁-C₈ alkyl, a substituted or unsubstitutedC₂-C₈ alkenyl, a substituted or unsubstituted phenyl, a substituted orunsubstituted alkyl-phenyl, or a substituted or unsubstituted C₁-C₈alkoxy; and wherein each occurrence of R⁷ is independently acarboxylate, a sulfate, a sulfonate, a nitrate, a phosphate, aphosphonate, or another negatively charged functional group; andphysically foaming the composition, forming a foam having a specificgravity of less than 0.7.

Feature 75. The method according to Feature 74, wherein the secondrepeat unit has a formula according to Formula IIA

Feature 76. The method according to any one of Features 74-75, whereinthe composition consists essentially of the plurality of ionomericcopolymers and cations.

Feature 77. The method according to any one of Features 74-76, whereineach occurrence of R¹ is none.

Feature 78. The method according to any one of Features 74-77, whereineach occurrence of R² is independently a hydrogen, methyl, phenyl, orchloride.

Feature 79. The method according to any one of Features 74-78, whereineach occurrence of R² is

where each occurrence of R⁴ is independently a hydrogen, a substitutedor unsubstituted C₁-C₈ alkyl.

Feature 80. The method according to any one of Features 74-79, whereineach occurrence of R³ is independently a hydrogen or methyl.

Feature 81. The method according to any one of Features 74-80, whereineach occurrence of R⁵ is independently a hydrogen or a methyl.

Feature 82. The method according to any one of Features 74-81, whereineach occurrence of R⁶ is none.

Feature 83. The method according to any one of Features 74-82, whereineach occurrence of R⁷ is a carboxylate.

Feature 84. The method according to any one of Features 74-83, wherein aratio II of a total parts by weight of the second repeat unit to a totalweight of the ionomeric copolymers is about 0.1 to about 0.6.

Feature 85. The method according to any one of Features 74-84, furthercomprising a plurality of olefinic polymers.

Feature 86. The method according to any one of Features 74-85, whereineach of the olefinic polymers is independently selected from the groupconsisting of an ethylene-based copolymer, a propylene-based copolymer,and a butene-based copolymer.

Feature 87. The method according to any one of Features 74-86, whereineach of the olefinic polymers is an ethylene-based copolymer.

Feature 88. The method according to any one of Features 74-87, whereinthe ethylene-based copolymer is selected from the group consisting of astyrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 89. The method according to any one of Features 74-88, whereinthe ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 90. The method according to any one of Features 74-89, whereinthe ethylene-vinyl acetate (EVA) copolymer has a vinyl acetate contentof about 10% to about 45%.

Feature 91. The method according to any one of Features 74-90, wherein aratio V of a total parts by weight of the olefinic polymers present inthe composition to a total parts by weight of the ionomeric copolymersin the composition is about 0.0 to about 0.6, about 0.0 to about 0.4,about 0.01 to about 0.4, or about 0.01 to about 0.6.

Feature 92. The method according to any one of Features 74-91, whereinthe ratio V is about 0.1 to 0.4.

Feature 93. The method according to any one of Features 55-92, whereineach of the plurality of cations is a metal cation.

Feature 94. The method according to any one of Features 55-93, whereineach of the metal cations independently selected from the groupconsisting of a magnesium ion, a sodium ion, a potassium ion, a cesiumion, a calcium ion, a barium ion, a manganese ion, a copper ion, a zincion, a tin ion, a lithium ion, an alkali metal, alkali earth metal, or acompound thereof.

Feature 95. The method according to any one of Features 55-94, whereineach of the plurality of cations is independently selected from thegroup consisting of sodium cation, a zinc cation, and a magnesiumcation.

Feature 96. The method according to any one of Features 55-95, whereineach of the plurality of cations is an organic cation.

Feature 97. The method according any one of Features 55-96, wherein eachof the organic cations is independently selected from the groupconsisting of an ammonium ion, a pyridinium ion, a guanidinium ion, animidazolium ion, a phosphonium ion, and a sulfonium ion.

Feature 98. The method according to any one of Features 55-97, whereinthe composition has a specific gravity of about 0.2 to about 0.35.

Feature 99. The method according to any one of Features 55-98, whereinthe composition has a specific gravity of about 0.1 to about 0.22.

Feature 100. The method according to any one of Features 55-99, whereinthe composition has an energy return of about 60% to about 85%.

Feature 101. The method according to any one of Features 55-100, whereinthe composition has an energy return of about 75% to about 90%.

Feature 102. The method according to any one of Features 55-101, whereinthe composition has a stiffness of about 40 N/mm to about 275 N/mm.

Feature 103. The method according to any one of Features 55-102, whereinthe composition has a stiffness of about 50 N/mm to about 85 N/mm.

Feature 104. The method according to any one of Features 55-103, whereinthe composition has a change in displacement at max loading of about0.75 mm or less when measured on foam slabs having a thickness of about1 cm, wherein the foam slabs are compressed for about 5000 cycles ofcompression from ON to 300 N and back to 0 N per cycle, using a 45 mmdiameter tupp as the compression head.

Feature 105. The method according to any one of Features 55-104, whereinthe composition has a change in displacement at max loading of about 0.1mm or less when measured on foam slabs having a thickness of about 1 cm,wherein the foam slabs are compressed for about 5000 cycles ofcompression from ON to 300 N and back to 0 N per cycle, using a 45 mmdiameter tupp as the compression head.

Feature 106. The method according to any one of Features 55-105, whereinthe article is substantially free of a chemical blowing agent anddecomposition product thereof.

Feature 107. The method according to any one of Features 55-106, whereinthe article is substantially free of covalent crosslinks between theionomers.

Feature 108. A method of forming a foam article, the method comprisingforming a melt of a first composition at a first pressure, wherein thefirst composition comprises one or more ionomeric copolymers, whereineach of the one or more ionomeric copolymers includes chain units of oneor more olefins and one or more ethylenically-unsaturated acid groups; aplurality of cations; and a fluid; introducing the melt to a secondpressure less than the first pressure, causing a portion of the fluid toleave the melt and forming a foam structure in the melt; andsimultaneously with the introducing or sequentially following theintroducing, cooling the melt to a temperature below a melting point ofthe first composition, causing a portion of the plurality of cations toionically crosslink anionic groups from the acid groups in the ionomericcopolymers, forming the foamed article.

Feature 109. The method according to Feature 108, wherein theintroducing comprises extruding the solution through a die, and thefoamed article is a strand of extruded foam.

Feature 110. The method according to any one of Features 108-109,wherein the introducing comprises injecting the solution into a mold,and the foamed article is an injection molded foamed article.

Feature 111. The method according to any one of Features 108-110,wherein the first composition further comprises a nucleating agent.

Feature 112. The method according to any one of Features 108-111,wherein the nucleating agent comprises a metal salt of a fatty acid.

Feature 113. The method according to any one of Features 108-112,wherein the nucleating agent comprises zinc stearate or other nucleatingagents described herein.

Feature 114. The method according to any one of Features 108-113,wherein the first composition comprises from about 0.1 wt. % to about 2wt. % of the nucleating agent based upon a total weight of thecomposition.

Feature 115. The method according to any one of Features 108-114,wherein the ionomeric copolymers are terpolymers of ethylene, methylacrylic acid, and acrylic acid.

Feature 116. The method according to any one of Features 108-115,wherein a ratio II of a total parts by weight of the acid groups in theionomeric copolymers to a total weight of the ionomeric copolymers isabout 0.1 to about 0.6.

Feature 117. The method according to any one of Features 108-116,wherein the ionomeric copolymers are copolymers of ethylene and acrylicacid.

Feature 118. The method according to any one of Features 108-117,wherein a ratio III of a total parts by weight of the acrylic acid inthe ionomeric copolymers to a total weight of the ionomeric copolymersis about 0.05 to about 0.6.

Feature 119 The method according to any one of Features 108-118, whereinthe ionomeric copolymers are copolymers of ethylene and methyl acrylicacid.

Feature 120. The method according to any one of Features 108-119,wherein a ratio IV of a total parts by weight of the methyl acrylic acidin the ionomeric copolymers to a total weight of the ionomericcopolymers is about 5% to about 20%.

Feature 121. The method according to any one of Features 108-120,wherein the first composition comprises one or more olefinic polymers.

Feature 122. The method according to any one of Features 108-121,wherein each of the one or more olefinic polymers is independentlyselected from the group consisting of an ethylene-based copolymer, apropylene-based copolymer, and a butene-based copolymer.

Feature 123. The method according to any one of Features 108-122,wherein at least one of the one or more olefinic polymers is anethylene-based copolymer.

Feature 124. The method according to any one of Features 108-123,wherein the ethylene-based copolymer is selected from the groupconsisting of a styrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 125. The method according to any one of Features 108-124,wherein the ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 126. The method according to any one of Features 108-125,wherein the ethylene-vinyl acetate (EVA) copolymer has a vinyl acetatecontent of about 10% to about 45%.

Feature 127. The method according to any one of Features 108-126,wherein a ratio V of a total parts by weight of the olefinic polymerspresent in the first composition to a total parts by weight of theionomeric copolymers present in the first composition is about 0.0 toabout 0.6, about 0.0 to about 0.4, about 0.01 to about 0.4, or about0.01 to about 0.6.

Feature 128. The method according to any one of Features 108-127,wherein the ratio V is about 0.1 to about 0.4.

Feature 129. A method of forming a foam article, the method comprisingforming a melt of a first composition at a first pressure, wherein thefirst composition comprises a plurality of ionomeric copolymers, whereineach of the ionomeric copolymers comprises a plurality of a first repeatunit having a formula according to Formula I and a plurality of a secondrepeat unit having a formula according to Formula II, and a plurality ofcations, and a fluid; introducing the melt to a second pressure lessthan the first pressure, causing a portion of the fluid to leave themelt and forming a foam structure in the melt; and simultaneously withthe introducing or sequentially following the introducing, cooling themelt to a temperature below a melting point of the first composition,causing a portion of the plurality of cations to ionically crosslink twoor more of the second repeat units, forming the foamed article.

Feature 130. The method according to Feature 129, wherein the firstcomposition consists essentially of the plurality of ionomericcopolymers and metal cations.

Feature 131. The method according to any one of Features 129-130,wherein each occurrence of R¹ is none.

Feature 132. The method according to any one of Features 129-131,wherein each occurrence of R² is independently a hydrogen, methyl,phenyl, or halogen.

Feature 133. The method according to any one of Features 129-132,wherein each occurrence of R² is

where each occurrence of R⁴ is independently a hydrogen, a substitutedor unsubstituted C₁-C₈ alkyl.

Feature 134. The method according to any one of Features 129-133,wherein each occurrence of R³ is independently a hydrogen or methyl.

Feature 135. The method according to any one of Features 129-134,wherein each occurrence of R⁵ is independently a hydrogen or a methyl.

Feature 136. The method according to any one of Features 129-135,wherein each occurrence of R⁶ is none.

Feature 137. The method according to any one of Features 129-136,wherein each occurrence of R⁷ is a carboxylate.

Feature 138. The method according to any one of Features 129-137,wherein a ratio II of a total parts by weight of the second repeat unitto a total weight of the ionomeric copolymers is about 0.1 to about 0.6.

Feature 139. The method according to any one of Features 129-138,wherein the first composition comprises a plurality of olefinicpolymers.

Feature 140. The method according to any one of Features 129-139,wherein each of the olefinic polymers is independently selected from thegroup consisting of an ethylene-based copolymer, a propylene-basedcopolymer, and a butene-based copolymer.

Feature 141. The method according to any one of Features 129-140,wherein each of the olefinic polymers is an ethylene-based copolymer.

Feature 142. The method according to any one of Features 129-141,wherein the ethylene-based copolymer is selected from the groupconsisting of a styrene-ethylene/butylene-styrene (SEBS) copolymer; anethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinylacetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; anethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE)copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof,and any blend thereof.

Feature 143. The method according to any one of Features 129-142,wherein the ethylene-based copolymer is an ethylene-vinyl acetate (EVA)copolymer.

Feature 144. The method according to any one of Features 129-143,wherein the ethylene-vinyl acetate (EVA) copolymer has a vinyl acetatecontent of about 10% to about 45%.

Feature 145. The method according to any one of Features 129-144,wherein a ratio V of a total parts by weight of the olefinic polymerspresent in the composition to a total parts by weight of the ionomericcopolymers present in the composition is about 0.0 to about 0.6, about0.0 to about 0.4, about 0.01 to about 0.4, or about 0.01 to about 0.6.

Feature 146. The method according to any one of Features 129-145,wherein the ratio V is about 0.1 to 0.4.

Feature 147. The method according to any one of Features 129-146,wherein each of the plurality of cations is a metal cation.

Feature 148. The method according to any one of Features 129-147,wherein each of the metal cations independently selected from the groupconsisting of a magnesium ion, a sodium ion, a potassium ion, a cesiumion, a calcium ion, a barium ion, a manganese ion, a copper ion, a zincion, a tin ion, a lithium ion, an alkali metal ion, an alkali earthmetal ion, or a compound thereof.

Feature 149. The method according to any one of Features 129-148,wherein each of the plurality of cations is independently selected fromthe group consisting of a lithium ion, a sodium cation, a zinc cation,and a magnesium cation.

Feature 150. The method according to any one of Features 129-149,wherein each of the plurality of cations is an organic cation.

Feature 151. The method according to any one of Features 129-150,wherein each of the organic cations is independently selected from thegroup consisting of an ammonium ion, a pyridinium ion, a guanidiniumion, an imidazolium ion, a phosphonium ion, and a sulfonium ion.

Feature 152. The method according to any one of Features 129-151,wherein the article has a specific gravity of about 0.2 to about 0.35.

Feature 153. The method according to any one of Features 129-152,wherein the article has a specific gravity of about 0.1 to about 0.22.

Feature 154. The method according to any one of Features 129-153,wherein the article has an energy return of about 60% to about 85%.

Feature 155. The method according to any one of Features 129-154,wherein the article has an energy return of about 75% to about 90%.

Feature 156. The method according to any one of Features 129-155,wherein the article has a stiffness of about 40 N/mm to about 275 N/mm.

Feature 157. The method according to any one of Features 129-156,wherein the article has a stiffness of about 50 N/mm to about 85 N/mm.

Feature 158. The method according to any one of Features 129-157,wherein the article has a change in displacement at max loading of about0.75 mm or less when measured on foam slabs having a thickness of about1 cm, wherein the foam slabs are compressed for about 5000 cycles ofcompression from ON to 300 N and back to 0 N per cycle.

Feature 159. The method according to any one of Features 129-158,wherein the article has a change in displacement at max loading of about0.1 mm or less when measured on foam slabs having a thickness of about 1cm, wherein the foam slabs are compressed for about 5000 cycles ofcompression from ON to 300 N and back to 0 N per cycle, using a 45 mmdiameter tupp as the compression head.

Feature 160. The method according to any one of Features 129-159,wherein the composition is substantially free of a chemical blowingagent or decomposition product thereof.

Feature 161. The method according to any one of Features 129-160,wherein the composition is substantially free of covalent crosslinksbetween the ionomers.

Feature 162. The method according to any one of Features 129-161,wherein the first pressure is about 25 MPa to 150 MPa.

163. The method according to any one of Features 129-162, wherein thesecond pressure is about 1 atm or less

Feature 164. The method according to any one of Features 129-163,wherein the melt is at a temperature of about 170° C. to about 235° C.

Feature 165. The method according to any one of Features 129-164,wherein the mold is at a temperature of about 25° C. to about 50° C.

Feature 166. The method according to any one of Features 129-165,wherein the melt is formed in an interior of a barrel.

Feature 167. The method according to any one of Features 129-166,wherein the barrel comprises a feedstock hopper in fluid communicationwith the interior of the barrel; wherein the first composition is in thefeedstock hopper and flows from the feedstock hopper into the interiorof the barrel.

Feature 168. The method according to any one of Features 129-167,wherein the interior of the barrel comprises a screw for mixing the meltwith the atmospheric gas to form the solution, and wherein the screwmixes the melt with the atmospheric gas to form the solution.

Feature 169. The method according to any one of Features 129-168,wherein the screw has a length of about 20 mm to about 50 mm.

Feature 170. The method according to any one of Features 129-169,wherein the barrel further comprises a nozzle at an end of the barrelopposite the feedstock hopper; and wherein the solution is injected intothe mold through the nozzle.

Feature 171. The method according to any one of Features 129-170,wherein the nozzle is at a temperature of about 180° C. to about 230° C.

Feature 172. The method according to any one of Features 129-171,wherein the fluid is an atmospheric gas or a supercritical fluidthereof.

Feature 173. The method according to any one of Features 129-172,wherein the atmospheric gas is N₂, CO₂, or a mixture thereof.

Feature 174. The method according to any one of Features 129-173,wherein the fluid is a supercritical fluid when it is mixed with themelt to form the solution.

Feature 175. The method according to any one of Features 129-174,wherein the article comprises a total parts by weight of the gas fromabout 0.1% to about 3% by weight based upon a total weight of thearticle.

Feature 176. The method according to any one of Features 129-175,wherein the fluid is N₂ or a supercritical fluid thereof, and whereinthe article comprises a total parts by weight of the N₂ from about 0.1%to about 0.3% by weight based upon a total weight of the article.

Feature 177. The method according to any one of Features 129-176,wherein the fluid is CO₂ or a supercritical fluid thereof, and whereinthe article comprises a total parts by weight of the CO₂ from about 1%to about 3% by weight based upon a total weight of the article.

Feature 178. The method according to any one of Features 129-177,wherein the melt comprises a recycled material of a recycled foamarticle comprising the first composition.

Feature 179. The method according to any one of Features 129-178,further comprising cutting or grinding the molded foam to produceparticulates, and melting the particulates into pellets to form therecycled material.

Feature 180. The method according to any one of Features 129-179,wherein the recycled foam article is an article according to any one ofFeatures 1-54.

Feature 181. The method according to any one of Features 129-180,wherein the melt is formed from about 50%, about 40%, about 30%, or lessof the recycled material from the recycled foam article.

Feature 182. The method according to any one of Features 129-181,wherein the melt is formed from about 50%, about 80%, or more of therecycled material from the recycled foam article.

Feature 183. The method according to any one of Features 129-182,wherein the melt is formed from about 100% of the recycled material fromthe recycled foam.

Feature 184. A foam article made by a process comprising cutting orgrinding a previously molded foam article to form particulates, whereinthe recycled foam article is an article according to any one of Features1-54; melting the particulates into pellets to form the recycledmaterial; and forming a foam article via a method according to any oneof Features 55-183, wherein the recycled material is used to form themelt of the first composition.

Feature 185. The foam article according to Feature 184, wherein the meltcomprises about 50%, about 80% or more of the recycled material of therecycled foam composition.

Feature 186. The foam article according to any one of Features 184-185,wherein the melt comprises about 100% of the recycled material of therecycled foam composition.

Feature 187. The foam article according to any one of Features 184-186,wherein the melt comprises about 50%, about 30%, or less of the recycledmaterial of the recycled foam composition.

Feature 188. The foam article according to any one of Features 184-187,wherein the foam composition has a specific gravity within about 5% of aspecific gravity of the recycled foam article when measured under thesame conditions.

Feature 189. The foam article according to any one of Features 184-188,wherein the foam article has energy return within about 5% of an energyreturn of the recycled foam article when measured under the sameconditions.

Feature 190. The foam article according to any one of Features 184-189,wherein the foam article has a stiffness within about 5% of a stiffnessof the recycled foam article when measured under the same conditions.

Feature 191. The foam article according to any one of Features 184-190,wherein the foam article has a change in displacement at max loadingwithin about 5% of a change in displacement at max loading of therecycled foam article when measured under the same conditions.

We claim:
 1. An article comprising a composition, wherein the composition comprises one or more ionomeric copolymers, wherein each of the one or more ionomeric copolymers includes chain units derived from one or more olefins and chain units derived from one or more ethylenically-unsaturated acid groups; and a plurality of organic cations, wherein the organic cations ionically crosslink anionic groups from the acid groups in the ionomeric copolymers.
 2. The article according to claim 1, wherein a ratio II of a total parts by weight of the one or more ethylenically-unsaturated acid groups in the ionomeric copolymers to a total weight of the one or more ionomeric copolymers is about 0.1-0.5.
 3. The article according to claim 1, wherein the one or more ionomeric copolymers are copolymers of ethylene, acrylic acid, and an acrylate.
 4. The article according to claim 3, wherein a ratio III of a total parts by weight of the acrylic acid in the one or more ionomeric copolymers to a total weight of the one or more ionomeric copolymers is about 0.05 to about 0.6.
 5. The article according to claim 3, wherein a ratio IV of a total parts by weight of the acrylate in the one or more ionomeric copolymers to a total weight of the one or more ionomeric copolymers is about 5% to about 20%.
 6. The article according to claim 1, wherein the composition further comprises one or more olefinic polymers.
 7. The article according to claim 6, wherein each of the one or more olefinic polymers is independently selected from the group consisting of an ethylene-based copolymer, a propylene-based copolymer, and a butene-based copolymer.
 8. The article according to claim 7, wherein at least one of the one or more olefinic polymers is an ethylene-based copolymer.
 9. The article according to claim 10, wherein the ethylene-based copolymer is selected from the group consisting of a styrene-ethylene/butylene-styrene (SEBS) copolymer; an ethylene-propylene diene monomer (EPDM) copolymer; an ethylene-vinyl acetate (EVA) copolymer; an ethylene alkyl acrylate (EAA) copolymer; an ethylene alkyl methacrylate (EAMA) copolymer; an ethylene-octene (POE) copolymer; an ethylene-butene (PEB) copolymer, any copolymer thereof, and any blend thereof.
 10. The article according to claim 6, wherein a ratio V of a total parts by weight of the one or more olefinic polymers present in the composition to a total parts by weight of the one or more ionomeric copolymers in the composition is about 0.01 to about 0.6.
 11. The article according to claim 1, wherein each of the one or more ionomeric copolymers comprises a plurality of a first repeat unit having a formula according to Formula I and a plurality of a second repeat unit having a formula according to Formula II,

wherein each of the cations is crosslinking two or more of the second repeat units; wherein each occurrence of R¹ is independently none, a substituted or unsubstituted C₁-C₈ alkyl, or a substituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence of R² is independently hydrogen, a halogen, a substituted or unsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy, or a substituted or unsubstituted C₃-C₁₂ alkyl ester; wherein each occurrence of R³ is independently hydrogen, a substituted or unsubstituted C₁-C₈ alkyl, or a substituted or unsubstituted C₂-C₈ alkenyl; wherein each occurrence of R⁵ is independently a hydrogen, a halogen, a substituted or unsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, a substituted or unsubstituted C₁-C₈ alkoxy, or a substituted or unsubstituted C₃-C₁₂ alkyl ester; wherein each occurrence of R⁶ is independently none, a substituted or unsubstituted C₁-C₈ alkyl, a substituted or unsubstituted C₂-C₈ alkenyl, a substituted or unsubstituted phenyl, a substituted or unsubstituted alkyl-phenyl, or a substituted or unsubstituted C₁-C₈ alkoxy; and wherein each occurrence of R⁷ is independently a carboxylate, a sulfate, a sulfonate, a nitrate, a phosphate, a phosphonate, or another negatively charged functional group.
 12. The article according to claim 11, wherein a ratio II of a total parts by weight of the second repeat unit to a total weight of the one or more ionomeric copolymers is about 0.1 to about 0.6.
 13. The article according to claim 12, wherein the composition further comprises one or more olefinic polymers.
 14. The article according to claim 13, wherein each of the one or more olefinic polymers is independently selected from the group consisting of an ethylene-based copolymer, a propylene-based copolymer, and a butene-based copolymer.
 15. The article according to claim 14, wherein at least one of the one or more olefinic polymers is an ethylene-based copolymer.
 16. The article according to claim 15, wherein the one or more olefinic polymers have a melt flow index of about 0.5-2.5.
 17. The article according to claim 16, wherein the composition has an energy return of about 75% to about 90%.
 18. The article according to claim 1, wherein the composition has an energy return of about 75% to about 90%. 